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<Search><pages Count="125"><page Index="1"><![CDATA[Contents



                  1.  Leaves                                                                                         9


                  2.  Plant Adaptations                                                                            18


                  3.  Animals and Their Young Ones                                                                 28






                  4.  Animal Adaptations                                                                           36


                  5.  Circulatory System and Excretory System                                                      47


                  6.  Food: Our Basic Need                                                                         54






                  7.  Digestion of Food                                                                            63



                  8.  Clothes                                                                                      73


                  9.  Air, Water and Weather                                                                       81






                 10.  The Solar System                                                                             91


                 11.  Keeping the Earth Green                                                                    101


                 12.  Soil                                                                                       106







                 13.  Solids, Liquids and Gases                                                                  115


                 14.  Force, Work and Energy                                                                     123]]></page><page Index="2"><![CDATA[Leaves


                          1












            Learning Objectives


                   To Understand:
                   •  Structure of a green leaf            •  How do plants prepare their food?
                   •  Why do leaves change their colour in winter?



                   To Find Out:
                   •  About photosynthesis

                   •  How leaves change their colour in winter?




            Let’s Begin

            Leaves have many different shapes and sizes. These green parts of plants can trap
            sunlight. They have tiny openings on their surface to allow the movement of water
            and air in and out. Leaves are mainly of two types– Simple leaves and Compound leaves.

            Given below are the pictures of simple and compound leaves.

            Simple leaves have a single and an
            undivided blade. The compound leaves
            are divided and several leaves axis on the
            same branch.                                                   Simple Leaf                Compound Leaf


            Identify whether the following leaves are simple or compound.



















                                                                                                                      9
                                                                                              Active Science-4]]></page><page Index="3"><![CDATA[S tructure of a Leaf

            A leaf is mostly a green, flattened

            structure  attached to the stem. The                      Veins                                  Blade
            leaves are also called the food factories
            of plants. The flat broad part of a leaf is                                                        Midrib

            called the lamina or blade. The single
            leaf blade connected to the stem is called
            the petiole. The leaf, has an outer waxy                                                       Petiole
            protective coating called the  cuticle.
            There are several veins in a leaf and the                                 Parts of a Leaf

            main vein is called the midrib. These veins
            carry water and nutrients within the leaf.              Closed stomata

            Like humans, plants also breathe. They
            do it through  tiny openings present on

            the surface of leaf  called stomata. The
            stomata open and close to allow the
            exchange of gases like carbon dioxide and
            the oxygen. Stomata also control the loss

            of water through leaves. The opening and
            closing of stomata  is controlled by the                                                  Open stomata
            bean-shaped guard cells.
                                                                             Stomata on the Surface of Leaf


                                                                H ow Do Plants Prepare Their Food?

                                                               Plants  make their own food through the
                                                               process of photosynthesis. Leaves are the
                                                 Oxygen
                                                               sites of photosynthesis. The photosynthesis
                                                               occurs in the  chloroplasts, the tiny
                                                               structures located in the cells of leaves and
             Energy from                             Food      green stems. The chloroplasts contain a

                sunlight                                       green coloured pigment called chlorophyll.
                                                               It is this chlorophyll which traps sunlight.

               Carbon                                          Thus, the things which are necessary for a
               dioxide                                         plant to carry out photosynthesis are:


                                                               •  Carbon dioxide            •  Light
                 Water
                                                               •  Water                     •  Chlorophyll

                                                               Plants make their own food in the form
                 Photosynthesis in Plants                      of sugar or glucose by absorbing the light




              10       Active Science-4]]></page><page Index="4"><![CDATA[energy of the sun. The sugar is stored  in the form of starch in the leaf for its own
            use and for animals.

            The carbon dioxide is taken in through the stomata. The water is absorbed from

            soil through the roots and carried to the plant parts by the stem. The process of
            photosynthesis can be shown as:
                                                                    Light
                              Carbon Dioxide + Water                            Sugar + Oxygen
                                                                 Chlorophyll


            Activity 1.1

            Aim                       :  To test a leaf for the presence of starch as food.

            Materials Required :  •  a burner/tripod stand/wire gauze                      •  a beaker

                                          •  boiling tube                                  •  tongs
                                          •  test tube holder                              •  white tile
                                          •  leaf to be tested (hibiscus leaves are excellent)

                                          •  90% ethanol                                   •  iodine solution

            Procedure                  :  1.  Take a green leaf  from  a plant that has  been exposed to
                                              sunlight for a few hours.


                                        2.  Half-fill a beaker with
                                              water. Heat the water
                                              until it boils. Maintain

                                              the water at the boiling
                                              point.


                                        3.  Use tongs to place the
                                              leaf in the boiling water.
                                              Boil for 2 minutes.


                                        4.  Turn off the burner.

                                        5.  Place the boiled leaf in a
                                              boiling tube containing

                                              90% ethanol.

                                        6.  Place the boiling tube in hot water and boil for 10 minutes or
                                              until the leaf decolourises.


                                        7.  Gently remove the leaf from the test tube and wash with a fine
                                              drip of cold tap water.



                                                                                                                    11
                                                                                             Active Science-4]]></page><page Index="5"><![CDATA[8.  Spread the leaf evenly on a white tile.

                                          9.  Add a few drops of iodine solution to the leaf and note the
                                                observations.


              Observation             :   The leaf would change its colour to blue-black.

              Conclusion              :   This change of colour to blue-black indicates the presence of starch.



              Why do Leaves Change Colour in Winter?

              During winter, leaves are unable to prepare food. There is no sufficient light or

              water for photosynthesis. They live off the food they synthesised and stored during
              summer. The chlorophyll disappears. The bright green colour slowly changes to
              yellow and then orange. Starch that was stored in the leaves as a by product of

              photosynthesis turns red due to cool temperature.



              Let’s Recapitulate

                  Fill in the blanks with only one word.

                  1.  The leaves turn _____________ during winters.
                  2.  During winter, there is no sufficient light and water for_____________.

                  3.  The opening and closing of stomata is controlled by_____________.

                  4.  _____________ has a waxy coating that protects the leaf.
                  5.  _____________ are the tiny structures located in the cells of leaves and green stems.




               I nterdependence of Plants and Animals


              Survival of  plants  and  animals  depends  entirely
              on how much they depend on each other. Through                              Factual Study
              the process of photosynthesis, plants prepare their                      Plants provide us food,

              own food. This food is a source of nourishment for                       shelter, fuel, building

              all other life forms. The leaves exhale oxygen which                     material, medicines, etc.
              is majorly required by humans and animals for                            Some plants have
              breathing. Therefore, animals and humans largely                         medicinal value as well.

              depend on plants.

              Animals may be – herbivorous, carnivorous and omnivorous. Herbivores eat plants,

              carnivores eat other small plant eating animals, and omnivores eat both plants and




              12       Active Science-4]]></page><page Index="6"><![CDATA[smaller animals. For example, crops are eaten by rats, rats are eaten by snakes
            and snakes are eaten by eagles. This chain that shows the interdependence of one
            animal on another for food is called the food chain.

















                                                           Food Chain


            Plants and animals co-exist to survive. They are dependent on each other. Carbon
            dioxide, oxygen, water, food and nutrients are exchanged between plants and animals.












                                         Carbon                                             Oxygen
                                         dioxide



                                   Plants and Animals Depend on Each Other


            The exchange of oxygen and carbon dioxide creates
            the inter-relationship between plants and animals.                    Let’s Pronounce Together

            This relation creates the balance in nature. If the  food chain                      oxygen       carbon
            number of plants decrease, the oxygen level will  dioxide                            photosynthesis

            decrease leading to increase in the level of carbon  chlorophyll
            dioxide. This will lead to extreme changes in weather.





                  Factual Study

                •  Some plants are carnivores. They get some nutrients by eating various small
                   insects and spiders. A well-known example of a carnivorous plant is the Venus Flytrap.

                •  The average strawberry has 200 seeds. It is the only fruit that bears seeds on the
                   outside.





                                                                                                                    13
                                                                                             Active Science-4]]></page><page Index="7"><![CDATA[LET’S
                   REVISE


                •  Leaves have various shapes and sizes.
                •  They are the food manufacturers of the plants.

                •  The flat part of the leaf is called blade or lamina.
                •  The leaf has a main vein called the midrib.

                •  The exchange of oxygen and carbon dioxide takes place through the stomata.
                •  Inter-relationship between plants and animals helps to keep balance in nature.




              Glossary
                   •  Photosynthesis    :   Photosynthesis is the process through which plants use

                                                  water, sunlight and carbon dioxide to make their food and
                                                  release oxygen in the air.

                   •  Cuticle                 :   The protective outer waxy coating of the leaf.
                   •  Petiole                 :   The stalk by which a leaf is attached to the stem.

                   •  Stomata                 :   Tiny openings on the leaf for the exchange of gases.

                   •  Chlorophyll             :   The green pigment in the leaves which gives green colour to
                                                  the leaves.

                   •  Food chain              :   A chain that shows the dependance of food of one organism
                                                  on another.





              Practice Time

                  A. Tick the correct option.

                  1.  The plants take carbon dioxide from the atmosphere through _____________.
                      a. roots                                             b. stems

                      c. flowers                                           d. leaves
                  2.  Which part of the plant takes in carbon dioxide from air for photosynthesis?

                      a. Vein of a leaf                                    b. Stomata

                      c. Roots                                             d. Sepals
                  3.  The food in plants, is stored as _____________.

                      a. starch                                            b. chlorophyll
                      c. oxygen                                            d. stomata





              14       Active Science-4]]></page><page Index="8"><![CDATA[4.  During respiration, plants use _____________ to release energy from their food.
                    a. carbon dioxide                                    b. oxygen

                     c. nitrogen                                         d. starch
                5.  The green colour of the leaf is due to a green pigment called _____________.

                     a. chlorophyll                                      b. midrib

                     c. petiole                                          d. blade

                B. Fill in the blanks.

                1.  _____________ need water, sunlight, carbon dioxide, minerals and nutrients for
                    survival.

                2.  Plants manufacture their food through the process of _____________.
                3.  _____________ animals only eat plants.

                4.  _____________  depend on smaller animals for food.

                5.  _____________ supports the plant above the soil.

                C. State whether the following statements are true or false:

                1.  Roots store food for future use.                                                           ______
                2.  Omnivores eat only plants.                                                                 ______

                3.  Oxygen is released during photosynthesis.                                                  ______

                4.  Plants are the basis of all food chains.                                                   ______

                5.  The interdependence between animals and plants is called food chain.                       ______

                D. Match the following:

                1.  Lamina                              a. tiny openings on the underside of leaves

                2.  Petiole                             b. the flat part of the leaf
                3.  Midrib                              c. the part which attaches leaf to the stem

                4.  Stomata                             d. the main vein of the leaf

                E. Give one word for each.

                1.  The process of making food in the green leaves of plants                           ____________

                2.  The interdependence of organisms on each other for food                            ____________

                3.  The outer part of a leaf that protects it.                                         ____________
                4.  The form in which food stores.                                                     ____________

                5.  The underside of leaf has tiny openings called this                                ____________








                                                                                                                    15
                                                                                             Active Science-4]]></page><page Index="9"><![CDATA[F. Identify and label the things involved in photosynthesis.












































                  G. Short Answer Questions.

                  1.  What do you mean by a food chain?
                  2.  Enlist the different parts of a leaf.

                  3.  Why do plants change their colour in winters?

                  4.  Draw a single food chain.

                  G. Long Answer Questions.

                  1.  What is photosynthesis?
                  2.  Why should be there balance in nature?

                  3.  How do plants make their food?
                  4.  What is the importance of veins in leaves?




              Think Hard

              1.  Why do leaves have different shapes?


              2.  Write the names of two plants used for medicinal purposes. Also write which diseases
                  are cured by them.



              16       Active Science-4]]></page><page Index="10"><![CDATA[Project Work


            Paste the pictures of a few fallen leaves that you collect from the school garden. Classify
            them as simple or compound leaves.




            Life Skills Activity

            Observe the given food chain. Similarly, make different food chains and wirte
            in the given space.










            ___________            ___________           ___________            ___________            ___________

            ___________            ___________           ___________            ___________            ___________
            ___________            ___________           ___________            ___________            ___________


            ___________            ___________           ___________            ___________            ___________




            Research and Development


            You have learnt the method to check the presence of starch in a leaf. Similarly, check the
            presence of starch in variegated leaves (leaves which are not completely green).




            Field Trip

            Visit a nearby park. Observe the different animals that you see. Try to make as many

            simple food chains as you can.





                 Net Work

              •  To know more about plants, log on to
                 http://www.catie.org.uk/PL_plant_life_page.html
              •  For an experiment, visit

                 http://www.education.com/science-fair/article/plants-nourished-juice-soda-milk/







                                                                                                                    17
                                                                                             Active Science-4]]></page><page Index="11"><![CDATA[Plant Adaptations

                          2












              Learning Objectives


                     To Understand:
                     •  Adaptations in plants               •  Aduatic and terrestrial plants
                     •  Plants in deserts, mountains, plains, marshy areas



                     To Find Out:
                     •  About different plant habitats

                     •  About different plant adaptations




              Let’s Begin

              The plants are an essential part of our environment. All living things depend on
              plants for their food.


              Colour the matching flower as you use each word to fill in the blanks.



                                                                                       Flower
                      Roots                                    Food                                           Stem
                                        Leaf











                1. The plant part which makes food is called _____________.
                2. A _____________ uses sunlight to make food.

                3. The trunk of the tree is a _____________.
                4. Seeds are made by _____________.

                5. The _____________ push water up the stems.


             18       Active Science-4]]></page><page Index="12"><![CDATA[The place where an animal or a plant lives is called its habitat. The characteristics
            which make an organism better suited for its environment is called adaptation.



             A daptations in Plants


            There are different kinds of plants which grow in different places. Each plant has
            a unique set of characteristics that help it to survive in that particular area.

            Plants can be categorised according to their habitat into – aquatic plants and

            terrestrial plants.


            Aquatic Plants
            Plants that grow and live in water are called aquatic plants. Aquatic plants are

            further divided into four sub-categories.

             1.  Floating Plants: These plants float in water as they are light and small in
                  size. They have air filled in their stems that helps them to float. Examples of

                  floating plants are duckweed, water lettuce and water hyacinth. The roots of
                  these plants directly absorb nutrients from water.


















                       Duckweed                           Water Lettuce                      Water Hyacinth

             2.  Fixed Plants:  Lotus and
                  water lily are some common

                  examples of fixed plants.
                  These aquatic plants are fixed

                  to the waterbed through their
                  strong roots but their flowers
                  are found floating on the water                    Lotus                        Water Lily

                  surface. These plants have long
                  and thin air-filled stalks, i.e., they are hollow from inside. They have stomata

                  on the upper side for breathing. They absorb nutrients from soil through their
                  roots. The waxy coating on their leaves prevent them from rotting. Their roots



                                                                                                                    19
                                                                                             Active Science-4]]></page><page Index="13"><![CDATA[help them to absorb nutrients from soil in the waterbeds. Many tasty dishes
                    can be made from the roots of fixed plants, like the lotus.

               3.  Underwater Plants: These plants remain completely submerged in water.

                    Examples are hydrilla, vallisneria and pondweed. Their leaves do not have
                    stomata, they breathe through their body surface. These plants have narrow

                    leaves which are thin and ribbon-like. This protects them from getting torn by
                    the force of strong water current.















                              Hydrilla                          Vallisneria                        Pondweed
                  These are non-flowering plants. They get nutrients from the soil in the

                    waterbeds through their tiny roots. These plants are life savers for several
                    aduatic animals as they provide oxygen during the process of photosynthesis.

                    These plants are also kept in aquariums.

               4.  Emergent Plants: These plants
                    are rooted at the bottom of the

                    waterbed, but their leaves and
                    stems extend out on the surface
                    of the water body. Bulrush,

                    arrowhead, cattail and sedges
                    are some examples of emergent                      Arrowhead                       Cattail
                    plants.


              Activity 2.1


              What would happen to the aquatic plants if all the water bodies get dried up? Think and
              discuss with your friends.



              Let’s Recapitulate


                  Fill in the blanks.
                  1.  The place where an animal or plant lives is called its _____________.

                  2.  Plants which grow and live in water are called _____________.


              20       Active Science-4]]></page><page Index="14"><![CDATA[3.  Hydrilla, vallisneria and pondweed are the examples of _____________.
                4.  Sedge is an example of a _____________ plant.


                    Factual Study
                Lotus can reach only 49 inches in height but it can spread 10 feet horizontally.




            Terrestrial Plants

            Plants which grow on land are called terrestrial plants. They get their name from
            the word terra which means land. Such plants grow in different surroundings

            like in plains, deserts and mountains.

            Let us read about them.

             1.  Plants in Deserts:  Plants which
                  grow in desert  are also called

                  xerophytes. Water and rainfall
                  are scarce in the deserts. Therefore,
                  they grow in hot and dry conditions.
                  The thick green stem of these plants
                  contains chloroplasts (like in leaves )

                  which make food. Desert plants have                          Cactus                 Palm Tree
                  long  roots which help in absorbing
                  groundwater.         The       leaves      are            Factual Study
                  reduced to thorns that prevent loss                   The seeds of many desert plants are
                  of water through the process called                   resistant to dry conditions and can

                  transpiration.  Cactus  and  palm                     remain dormant for many years.
                  trees are examples of such plants.

                                                       2.  Plants on Mountains and Hill Slopes:

                                                            Plants and trees which grow on mountains
                                                            are called coniferous trees. These trees grow

                                                            in very cold temperatures. These are tall and
                                                            conical in shape. This conical shape allows
                                                            the sliding of the snow from their branches.

                                                            These trees have cones instead of flowers.
                                                            Their leaves have a waxy coating and are

                 Pine Tree                                  needle-shaped. This characteristic saves them
                                                            from rotting under snow in winters. The pine,
                                                            fir and deodar are examples of such plants.
                                       Deodar Tree


                                                                                                                    21
                                                                                             Active Science-4]]></page><page Index="15"><![CDATA[3.  Plants in Plains: These
                    plants can survive in cold

                    as well as hot climate
                    conditions. These have lots
                    of branches with plenty of

                    leaves and flowers and shed
                    their leaves during winter.                   Banyan Tree                     Mango Tree
                    Mango, sheesham, peepal,

                    banyan and sal are the examples of such plants.

                                              4.  Plants in Marshy Areas: Plants which grow in
                                                   marshy areas are called  mangroves. The soil in

                                                   marshy areas is sticky and clayey, covered with water.
                                                   Such plants grow breathing roots out of the marsh.
                                                   Avicennia and Rhizophora are the examples of such


                     Rhizophora Plant              plants.
               5.  Plants in Evergreen Forests:
                    The plants which grow in evergreen

                    forests grow tall with rich leaves.
                    They can confine sunlight for

                    photosynthesis and produce food
                    in huge amount for themselves as
                    well as for animals. These plants

                    have waxy surface on leaves which                         Forest
                    help the rain to drain off from them.                                              Coconut Tree

                    Such forests are warm in climate and receive heavy rainfall throughout the
                    year. The trees do not shed their leaves in winters and are called as
                    evergreen leaves. Examples of these plants are pineapple, banana and

                    coconut.

               6.  Insectivorous  Plants:  Plants
                    which feed on small insects for

                    nutrition are called insectivorous
                    plants. These plants live in
                    habitats where soil lacks nutrients.

                    They get these deficient nutrients
                    by consuming insects. Pitcher,                         Venus Flytrap
                    Venus flytrap and Sundew are examples of such plants.                                Bladderwort



              22       Active Science-4]]></page><page Index="16"><![CDATA[These plants have a unique way to capture their prey – the trap is a bladder
                  that creates a vacuum that sucks in insects.

                  1.  The Pitcher Plant is a pitcher-shaped plant. A sticky substance is secreted

                      from its edges which makes the insect sitting on it slip inside the pitcher
                      hence, getting trapped.

                  2.  The Venus Flytrap has two lobes which have spikes on their edges. As soon
                      as an insect sits on it, the lobes shut, thus entrapping the insect.

                  3.  A Bladderwort vacuums its prey into a special bag where it is digested.

                      The bag even has a seal that snaps shut once the prey is inside. The trap
                      usually secretes sugars that lure insects.


            Activity 2.2

            Find out about the plant life existing in very cold places like Arctic zones.


             7.  Non-green Plants: Non-green plants make their food

                  from dead plants and animals. They do not contain
                  the green pigment called  chlorophyll. Therefore,
                  they cannot carry out photosynthesis. You must have
                  seen tiny mushrooms growing on dead decaying plant

                  matter.

             8.  Parasitic Plants:  Parasitic plants grow on an                                           Mushroom
                  another plant called host plant and derive nutrients from it. They grow special

                  roots that penetrate the body of the host plant, slowly and steadily killing it.
                  Cuscuta and Mistletoe are examples of such plants.

                       Factual Study
                     The tallest cactus is situated in the USA. It is about 67 feet high.






            Let’s Recapitulate


                State whether the following statements are true or false:
                1.  Plants which grow in dry areas are called mangroves.                                       ______

                2.  Plants which grow on mountains are called non-green plants.                                ______
                3.  Parasitic plants grow on other plants and take nutrients from them.                        ______

                4.  Parasitic plants do not have the green pigment.                                            ______
                5.  Plants which grow on land are called terrestrial plants.                                   ______



                                                                                                                    23
                                                                                             Active Science-4]]></page><page Index="17"><![CDATA[LET’S

                    REVISE


                •  Plants grow in different areas like mountains, oceans, deserts, forests, etc.
                •  The place where an animal or a plant lives is called its habitat.

                •  The characteristics that make an organism better suited to its environment are
                   called adaptations.                                              Let’s Pronounce Together

                •  Plants that grow and live in water are called aquatic
                   plants.                                                          habitat             aquatic
                                                                                    terrestrial         marshy
                •  Plants which grow on land are called terrestrial
                   plants. They get their name from the word terra                  parasitic           mangroves

                   which means land.                                                insectivorous       coniferous
                •  Plants which feed on small insects for nutrition are called insectivorous plants.

                •  The plants that grow on other plants and take nutrients from them are called parasitic
                   plants.




              Glossary

                   •  Aquatic plants                :  Plants that grow and live in water.
                   •  Terrestrial plants            :  Plants which grow on land.

                   •  Insectivorous plants  :  Plants which feed on small insects.
                   •  Parasitic plants              :  The plants that grow on other plants and derive nutrients
                                                      from them.

                   •  Coniferous trees              :  Plants and trees which grow on mountains.
                   •  Xerophytes                    :  Plants which grow in deserts.
                   •  Mangroves                     :  Plants which grow in marshy areas.

                   •  Deserts                       :  A desert is a dry, barren and hot area.

                   •  Mountains                     :  Mountains are a large landform that stretches above the
                                                      surrounding land in a limited area.

                   •  Plains                        :  A large area of flat land with few plants.




              Practice Time

                  A. Tick the correct option.

                  1.  The plants which grow in water are called _____________.
                      a. aquatic plants                                    b. floating plants

                      c. terrestrial plants                                d. parasitic plants


              24       Active Science-4]]></page><page Index="18"><![CDATA[2.  Which plants do not have stomata?
                     a. Fixed plants                                     b. Emergent plants

                     c. Underwater plants                                d. Floating plants
                3.  Plants which feed on small insects for nutrition are called _____________.

                     a. floating plants                                  b. terrestrial plants
                     c. insectivorous plants                             d. underwater plants

                4.  The plants lacking chlorophyll are called _____________.
                    a. non-green plants                                  b. parasitic plants

                     c. underwater plants                                d. emergent plants

                B. Fill in the blanks.

                1.  The place where an animal or a plant lives is called its _____________.
                2.  Plants float in water because of _____________ filled in their stems.

                3.  Plants that grow on other plants and take nutrients from them are called
                    _____________.
                4.  Mango, sheesham, peepal, banyan and sal are the examples of _____________.


                C. State whether the following statements are true or false.
                1.  Plants which grow in desert are also called xerophytes.                                    ______

                2.  Plants that grow and live in water are called parasitic plants.                            ______

                3.  The flowers of fixed plants are found on the water surface.                                ______
                4.  Terrestrial plants grow in plains, deserts and mountains.                                  ______

                5.  Mangroves is another name for the plants that grow in marshy lands.                        ______
                6.  Plants that grow in mountains are called xerophytes.                                       ______


                D. Match the following:
                1.  Hydrilla                                   a. plains


                2.  Mango                                      b. underwater plant

                3.  Avicennia                                  c. marshy

                4.  Coconut                                    d. emergent


                5.  Duckweed                                   e. mountains

                6.  Bulrush                                    f. deserts

                7.  Palm                                       g. floating


                8.  Pine                                       h. forests




                                                                                                                    25
                                                                                             Active Science-4]]></page><page Index="19"><![CDATA[E. Identify and name these plants. Also write their habitats.















                  _____________                                         _____________


                  _____________                                         _____________



                                             _____________                                          _____________


                                             _____________                                          _____________

                  F. Give one word for each.
                  1.  Bulrush, cattail and sedges are examples of                                        ____________

                  2.  Plants which grow in marshy areas are called                                       ____________
                  3.  The changing process by which an organism becomes better
                      suited to its environment is called                                                ____________

                  4.  Fixed plants absorb nutrients from the soil through their                          ____________

                  5.  Shape of trees in mountainous areas                                                ____________

                  G. Short Answer Questions.

                  1.  What is a habitat?
                  2.  List different types of aquatic plants.

                  3.  Give one example each of a plant growing in plains, mountains and deserts.
                  4.  What is unique about insectivorous plants?
                  5.  What are parasitic plants?

                  6.  Live examples of some emergent plants.

                  7.  What are mangroves?

                  H. Long Answer Questions.

                  1.  Write a short note on any two kinds of aquatic plants.
                  2.  What are the basic differences between aquatic, terrestrial and insectivorous
                      plants?
                  3.  Describe non-green plants.

                  4.  What are xerophytes? Explain.

                  5.  Write a note on insectivorous plants.

              26       Active Science-4]]></page><page Index="20"><![CDATA[Think Hard

            Why are some plants classified as indoors?




            Project Work

            Collect  pictures  of  various  plants  from  old  newspapers  and  magazines.  Group  them
            according to their habitat and paste them in your scrapbook.




            Life Skills Activity

            Ask your gardener for help and plant at least three outdoor plants and two indoor plants.

            Note the differences while taking care of them.




            Research and Development
            Find out some rare species of plants and their habitats and share in class.




            Field Trip

            Locate a pond nearby and visit it to study the different types of plants growing there.




                 Net Work

             •  Create a habitat of your own by logging on to http://switchzoo.com/games/
                 habitatgame.htm

             •  To play and attempt a quiz, visit http://www.bbc.co.uk/schools/scienceclips/ages/6_7/
                 plants_animals_env.shtml




























                                                                                                                    27
                                                                                             Active Science-4]]></page><page Index="21"><![CDATA[Animals and Their


                          3                       Young Ones












              Learning Objectives


                     To Understand the Characteristics of:
                     •  Animals that lay eggs               •  Animals that give birth to babies
                     •  Mammals and care of young ones


                     To Find Out:
                     •  Structure of an egg                 •  What is incubation?

                     •  About metamorphosis



              Let’s Begin


              Identify and write the names of the given young ones.
















                 _____________                                           _____________
                                             _____________                                           _____________


              Living things cannot live forever. They die after completing their life span. For

              life to go on, they produce young ones of their own kind. The process of producing
              babies of their own kind is called reproduction. The living things reproduce in
              two different ways – some give birth to young ones and some lay eggs.








             28       Active Science-4]]></page><page Index="22"><![CDATA[A nimals That Lay Eggs

            Animals that lay eggs are called oviparous animals. The parent animals sit on
            the eggs to keep them warm. This is known as incubation. Frog, fish, snake,

            lizard and insects like cockroach and butterfly are examples of animals which
            reproduce by laying eggs.


            Birds

            Birds reproduce by laying eggs in their nests. They sit on the eggs to keep them
            warm. The eggs then hatch and chicks come out. When they come out, they cannot
            fly as they are featherless. Their parents take care of them until they develop

            feathers and learn to fly.














                        Hen sits over eggs to keep them warm                                Hen with chicks

            Structure of an Egg

            The internal structure of all the eggs produced by
            birds is similar. The egg-shell is the outer layer                                              Egg Shell
            of the egg that protects its inner contents. The

            jelly-like white coloured material inside the egg                                                 Albumen
            shell is called albumen. The yellow-part present
            inside the albumen is called yolk. The yolk has

            all the nutrients which are necessary for the                                                       Yolk
            development of an embryo or the growing baby.
            The embryo develops into the young one. The

            stages of development from an embryo to an adult
            form the life cycle of an animal.

                                                                                               Egg
                                       Fish

                                       Fish lay hundreds of eggs in water at a time. They take care
                                       of their eggs but only a few eggs develop into babies because

                                       some are eaten by larger fish or other animals. The source of
                                       warmth for incubation of fish eggs are the sunrays.




                                                                                                                    29
                                                                                             Active Science-4]]></page><page Index="23"><![CDATA[Frog

              Frogs also lay large number of eggs in
              water. These eggs look like a huge bunch

              of jelly-like fluid which is known as                    Eggs (Spawn)          Tadpole
              spawn. These eggs hatch and develop                               LIFE CYCLE

              into  tadpoles. Tadpoles are extremely                             OF A FROG
              different in appearance as compared to                                                         Tadpole
              an adult frog. The change of tadpole to an                                                    with legs

              adult is called  metamorphosis. After
              metamorphosis, the tadpole becomes an
              adult frog.                                             Adult Frog          Young Frog






                                                               Butterfly

                                                               Butterflies       have      a    unique       way      of
                                                               reproduction.They lay their eggs on a leaf.
               Eggs                        Catterpiller        The larva, a small worm-like creature, comes

                        LIFE CYCLE                             out from the egg known as  caterpillar.
                     OF A BUTTERFLY                            The larva eats plenty of leaves for growth
                                                               and  develops a  protective covering around

                                                               itself. It is called a pupa. The pupa sheds its
                                                               skin several times and this process is called
                                                               moulting. The adult butterfly breaks free

                                                               from the pupa.
                 Butterfly                    Pupa


                      Factual Study
                  •  The global egg industry destroys 6,000,000,000 newborn male chicks every year.
                  •  Newborn chicks are more intelligent, alert and aware of their environment than
                      human toddlers.

                                                                                                             No wings
              Cockroaches and Grasshoppers
              There are three main stages in the life cycle of                    Egg
              cockroaches and grasshoppers. First stage is
                                                                                       LIFE CYCLE
              the formation of nymph, i.e., the larva comes                        OF A GRASSHOPPERS
              out when the eggs hatch. They resemble a lot                                                     Nymph

              to their parents. After the process of moulting
              several times, they develop into adults.
                                                                                    Adult
              30       Active Science-4]]></page><page Index="24"><![CDATA[Reptiles

            Snakes and lizards are reptiles that lay their eggs on the ground. But only some
            eggs from the total number of eggs laid, hatch with the help of the warmth from

            the sun. The rest are eaten by other animals.

                                                                  Factual Study

                                                              •  Grasshoppers produce music by

                                                                  rubbing their hindlimbs together.

                                                              •  Grasshoppers have ears on their
                                                                  bellies.


             A nimals Which Give Birth to Babies

            Mammals are the animals that give birth to young ones.
            They suckle their young ones with their milk after the birth.

            Some common examples of mammals are cats, monkeys,
            elephants, kangaroos, human beings, etc.                                                      Monkey

                                               The young ones of the mammals develop completely
                                               inside the mother’s body. When they are born, they have

                                               hair on the body, they have well-developed brain, and
                                             lungs to breathe. Some mammals like whales, dolphins,
                                        etc., live in water. But most of the mammals live on land.

                                      Dog, cow, monkey and rabbits are some examples of  land
                      Dolphin
                                     mammals. Whales and dolphins are the water mammals. They
                                  are also called aquatic mammals.

            Most mammals take care of their babies for long time. They

            keep them safe, clean and provide them food. Mammals like
            fish, whales, etc., do not take care of their young ones. They
            leave them on their own.
                                                                                                       Rabbit


            Let’s Recapitulate
                                                                                   Factual Study
                Fill in the blanks.
                                                                               •  Dolphins are intelligent
                1.  The larva that hatch from their eggs are called                animals that display a wide
                    ______________.                                                range of unique behaviours.

                2.  Snakes  and lizards lay  their eggs on the                 •  Sharks lay the biggest eggs in
                    ______________.                                                the world.





                                                                                                                    31
                                                                                             Active Science-4]]></page><page Index="25"><![CDATA[3.  Animals which give birth to young ones and feed them with their milk are called
                      ______________.
                  4.  The larva of a butterfly that develops into a ______________.

                  5.  The frog’s egg develop into ______________.



                    LET’S
                   REVISE



                •  Living things cannot live forever. They die after completing their life span.

                •  The parent animals sit on their young ones to keep them warm.
                •  Frog’s eggs look like a huge bunch of jelly.

                •  Frog’s eggs develop into a tadpole.

                •  The larva that comes out from the eggs of grasshoppers and cockroaches is called
                   nymph. They resemble their parents. After moulting many times, it converts into an
                   adult.                                                       Let’s Pronounce Together

                •  Animals which give birth to young ones and feed
                   them with their own milk are called mammals.                 incubation            metamorphosis
                                                                                caterpillar           embryo
                •  Butterflies lay their eggs on leaves of plants. The          nymph                 mammals
                   larva that comes out eats these leaves to grow.              pupa                  yolk




              Glossary
                   •  Reproduction                  :   Some animals give birth to their young ones and some
                                                      lay eggs.

                   •    Oviparous animals           :   Animals that lay eggs for reproduction.
                   •    Incubation                  :   The parent animals sit on their young ones to keep
                                                      them warm.

                   •    Spawn                       :   A huge bunch of jelly-like frog eggs.

                   •    Life cycle of an animal  :   The stages of development from an embryo to an adult.
                   •    Albumen                     :   The jelly-like white coloured material inside the egg shell.

                   •    Mammals                     :   Animals which give birth to young ones and feed them
                                                      with their milk.
                   •    Metamorphosis               :   The transformation process from a young one to an adult.

                   •  Moulting                      :   Shedding of old skin by an animal.
                   •    Yolk                        :   The yellow-part inside the albumen.

                   •    Nymph                       :   The larva that comes out from their eggs.




              32       Active Science-4]]></page><page Index="26"><![CDATA[Practice Time

                A. Tick the correct option.

                1.  The parent animals sit on eggs to keep them warm. This is known as _____________.
                    a. incubation                                        b. reproduction

                    c. egg-laying                                        d. nymph
                2.  The jelly-like white coloured material inside the egg shell is called _____________.
                    a. yolk                                              b. albumen

                    c. shell                                             d. larva

                3.  The transformation from young one to an adult is called _____________.
                    a. metamorphosis                                     b. incubation
                    c. reproduction                                      d. mammals

                4.  Frog eggs look like a huge bunch of jelly known as _____________.
                    a. spawn                                             b. tadpole

                    c. caterpillar                                       d. pupa
                5.  Mammals have well-developed _____________.

                    a. claws                                             b. tails

                    c. brains                                            d. hands

                B. Fill in the blanks.

                1.  When the chicks come out, they cannot fly as they are _____________.
                2.  The outer layer of the egg which protects the contents of the egg is called
                    _____________.
                3.  The yolk has all the nutrients which are necessary for the development of a growing
                    baby called _____________.

                4.  Snakes and lizards lay their eggs on _____________.

                C. State whether the following statements are true or false:

                1.  The transformation from young one to an adult is called incubation.                       ______

                2.  Animals which give birth to young ones and feed them with
                    their milk are called oviparous.                                                          ______
                3.  The yellow part inside the albumen is called shell.                                       ______

                4.  Reproduction is the process of producing young ones.                                      ______

                5.  Reptiles lay their eggs on the ground.                                                    ______









                                                                                                                    33
                                                                                             Active Science-4]]></page><page Index="27"><![CDATA[D. Match the following:

                  1.  Birds                                      a. water

                  2.  Snakes                                     b. leaves

                  3.  Butterflies                                c.  ground

                  4.  Fish                                       d. nest

                  5.  Grasshoppers                               e.  mammal


                  6.  Whales                                     f.  baby

                  7.  Human beings                               g. nymph

                  E. Label the given life cycle of a frog.












                                                            LIFE CYCLE
                                                             OF A FROG












                  F. Give one word for each.

                  1.  The outer layer of the egg which protects the contents of
                      the egg is called                                                                  ____________

                  2.  The transformation from young to an adult is called                                ____________
                  3.  The larva that comes out from the eggs                                             ____________

                  4.  A cluster of eggs laid by a frog                                                   ____________

                  5.  Animals that give birth to their young ones                                        ____________
                  6.  The young ones of a frog are called                                                ____________


                  G. Short Answer Questions.
                  1.  What is incubation?

                  2.  What is reproduction?

                  3.  Write the names of animals who lay their eggs on the ground.



              34       Active Science-4]]></page><page Index="28"><![CDATA[4.  What do you understand by albumen?
                5.  What is an embryo?

                6.  Define metamorphosis.

                H. Long Answer Questions.

                1.  Explain the life cycle of a butterfly.
                2.  Write a note on reproduction in a frog.

                3.  What are mammals? Enlist any two characteristics.

                4.  Differentiate between oviparous and viviparous animals.

                I.  Show with the help of a diagram.

                1.  Structure of an egg.                                Net Work
                2.  Life cycle of a butterfly.                      •  To see video of life cycle of a butterfly, log

                                                                        on to https://www.youtube.com watch?v=
                                                                        7AUeM8MbaIk
            Think Hard

             1.  Do all the young ones resemble their parents? Why or why not?

             2.  Mammals like fish, whales, etc., leave their young ones on their own. Why?




            Project Work

            Prepare a clay model of the different life stages of a butterfly to make its life
            cycle.




            Life Skills Activity

            Take a chart paper and divide it into two parts. Paste the pictures of animals that lay

            eggs on one side and animals that give birth to their young ones on the other side. Find
            out about how many take care of their young ones.




            Research and Development

            Suppose a cat in your house gives birth to its young ones. You have to observe how the
            cat is looking after its kittens. Find out more ways on how to take care of the kittens.




            Field Trip

            Look around a park or garden. Spot as many insects as you can. Identify the life stage of

            the different insects.

                                                                                                                    35
                                                                                             Active Science-4]]></page><page Index="29"><![CDATA[Animal Adaptations

                          4












              Learning Objectives


                     To Understand:
                     •  Adaptation in animals                    •   Extinct and endangered animals


                     To Find Out:
                     •  About terrestrial, aquatic, aerial and arboreal animals
                     •  What are herbivores, carnivores, omnivores and scavengers?

                     •  Different types of adaptation and how animals protect themselves.




              Let’s Begin

              Different animals have different characteristics. Some animals live in hot climate,
              some in cold and some in extremely cold regions. Fur is the hair which keeps

              animals warm in cold regions.

              Tick the animals who have fur and cross the ones who don’t have.































             36       Active Science-4]]></page><page Index="30"><![CDATA[A daptations in Animals

            Every organism undergoes a change over a period of time to adapt to its surroundings.
            Animals too change. The characterstics which make an organism to adjust and survive
            in its surroundings is called adaptation. The animals adapt to their environment
            for their survival. Let us study about different animals and their adaptations.


            Adaptations to Environment
            The different natural surroundings where different animals live are called its
            habitat. On the basis of different habitats, animals are categorised as terrestrial,
            aerial, aquatic and arboreal.


            Terrestrial Animals

            The animals that live on land in different climatic
            conditions are called terrestrial animals. Horses,
            camels, bears, foxes, humans are examples of such
            animals.
            Animals that live in cold regions like polar bear,                   Polar Bear

            fox, penguins have a thick coat of fur to keep them
            warm because polar regions are extremely cold.
            Animals living there have a thick layer of fat under
            the skin to protect them from cold. This layer is
            called blubber.
                                                                                                                  Yak
            Animals like bears sleep for a long time in winter
            because of scarcity of food, and therefore, they
            remain inactive during cold weather. This long
            winter sleep is called hibernation.


            For most of the time of the year, mountains are                                             Sheep
            also very cold. Animals like mountain sheep, goat, yak, etc., have thick fur on their
            body that keeps them warm during cold weather. These animals also have strong
            hooves, a major help in walking on the mountainous slopes.


                                                           Camels, lizards and desert snakes are desert
                                                           animals. Deserts usually have extreme hot
                                                           weather. Animals who live in desert have thick
                                                           skin and less hair on their body, which help
                                                           them to prevent water loss from their body.
            Lizard
                                                           Snails, lizards and earthworms sleep for a long
                                                           time in summer to escape from the heat. This
                                                           long summer sleep is called aestivation.
                          Snake



                                                                                                                    37
                                                                                             Active Science-4]]></page><page Index="31"><![CDATA[Aquatic Animals

              Aquatic animals are the animals
              living in water. Fish, turtle, whale

              and dolphin are some examples of
              aquatic animals. These animals can                                                           Fish

              swim easily because they have fins.                  Turtle
              Whales and turtles have paddle-like                                   Factual Study
              flippers that help them to swim across                            •  A cockroach can live for several

              water. Most aquatic animals have                                      weeks without its head.
              gills which help them in breathing.                               •  Starfish do not have a brain.



                                                    Amphibians
                                                    Animals that can live both in water as well as on land

                                                    are known as amphibians. Most of the amphibians
                                                    have lungs to breathe  on land and moist skin to

                                                    breathe underwater. Frog is an example of such an
              Frog                                  animal. It has strong hind limbs which help it to hop
                                      Webbed        on land and webbed feet which help it in swimming.
                                        feet



              Aerial Animals
              Aerial animals are the animals that can fly in the

              air. Bats, butterflies and dragonflies are examples                                         Bat
              of aerial animals. These animals have wings and
              feathers that help them to fly. Hollow bones and

              a boat-shaped body further help them in their
              flight. Butterflies and dragonflies are the insects
              that have paper-like wings which help them to fly.

                                                                                                        Butterfly


                                                     Arboreal Animals

                                                     Arboreal animals are animals like monkeys,
                                                     squirrels, tree lizards, etc., that spend most of their

                                                     time on trees. While climbing, their strong limbs
                                                     and sharp claws help them. A long and curly tail of a
               Monkey                                monkey helps it to hang from the branches of trees.


                                      Squirrel


              38       Active Science-4]]></page><page Index="32"><![CDATA[Let’s Recapitulate

                State whether the following statements are true or false:

                 1.  Thick layer of fat under the skin to keep an animal warm is called blubber.   ______
                2.  Fish, turtle, etc., are polar animals.                                                     ______

                3.  Hooves are a major help to the animals in walking over
                    the mountainous slopes.                                                                    ______

                4.  The animals that live on land in different climatic conditions
                    are called terrestrial animals.                                                            ______
                5.  Aerial animals are the animals that can fly in deserts.                                    ______


                                                                                  Factual Study
            Adaptations for Food
                                                                              •  Frogs cannot vomit. Whenever
            Different animals have different eating habits.                       a frog has to vomit absolutely, it

            Therefore, animals are categorised on the basis                       vomits its entire stomach.
            of the type of food they eat.                                     •  Giraffes and humans have the same

                                                                                  number of bones in their necks.
                                                    Herbivores

                                                    Plant-eating animals are called herbivores. Cows,
                                                    goats and giraffes are a few examples of such

                                                    animals. These animals have broad and strong
                                                    front teeth which help them in biting off the grass
                                                    and leaves. They also have strong teeth at the back
                                                    which help them in grinding. They have long and

                                                    strong legs to run a long distance in search of food.


            Carnivores
            Flesh-eating animals are called  carnivores. Tiger, lion
            and cheetah are examples of such animals. They have long

            and sharp canines to tear the flesh of their prey. They also
            have flat grinding teeth at the back of the mouth to chew
            the flesh and bones. The birds like eagles, who eat flesh

            have sharp beak and claws to catch other animals.


                                      Omnivores
                                      Animals who eat plants as well as flesh of other animals are
                                      called omnivores. Crow, humans and bears are example of

                                      such animals.



                                                                                                                    39
                                                                                             Active Science-4]]></page><page Index="33"><![CDATA[Scavengers

                                                     Animals that feed on the remains of dead animals
                                                     are called scavengers like jackal, hyena, wild dogs,

                                                     etc.


                                                     Parasites

                                                     Parasites depend and live on or inside the body
                                                     of other living beings for food. The host organism
                             Hyena
                                                     provides them the required nutrition. Lice, ticks

                                                     mosquitoes, bugs, hookworms are some examples of
                                                     such animals.

                                                     Some animals like ticks, lice and flea live on the

                                                     surface of the host body. These animals are adapted
                 Flea                                to suck blood from the host body with the help of
                                                     sucking tubes.
                                Tick


              Adaptations For Protection

              There are different types of adaptations that show how animals protect themselves
              from danger.

                  1.  Deer, rabbits and mice can protect themselves from danger and enemies by

                       running very fast.

                  2.  Whales, elephants and hippos have thick skin which help them to protect
                       themselves from hot climate.


                  3.  Cockroaches also have a hard outer body that protects them.

                  4.  Animals like crabs and turtles have a hard shell that protects their inner
                       soft body from danger.


                  5.  Porcupines have sharp spines as a shield from the enemies.

                  6.  Summer sleep in animals such as snail, lizard and earthworm is called
                       aestivation and winter sleep  in animals  of polar regions is  called

                       hibernation.

              Some animals have unique characteristics. They blend or mix themselves with
              their surroundings. This is called  camouflage. There are many animals that

              camouflage themselves while catching their prey or escaping from enemies.



              40       Active Science-4]]></page><page Index="34"><![CDATA[1.  Leopards, tigers and lions blend themselves
                     with the surroundings, especially  in the

                     grasslands because they have stripes and
                     spots on their bodies.

                 2.  A polar bear’s thick white coat allows it to

                     blend itself with snow, helping it to hide
                     and be safe from the hunters.
                                                                                  Leaf Insect
                 3.  Some insects like the leaf insect and the stick

                     insect completely camouflage themselves
                     against their background.

                 4.  Chameleons have an extensive feature of

                     changing colour. They change their colour
                     according to the surroundings. They can
                     look into all the directions and each eye ball

                     can look independently of each other.                                               Stick Insect




             E xtinct And Endangered Animals

                                                   Animals or species that no longer exist on earth are

                                                   called extinct animals. Dodos, passenger pigeons,
                                                   Caribbean monk seals, tecopa pupfish are some
                                                   examples of these animals.


                                                   Animals get extinct when they cannot adapt to their
                                                   surroundings. Dinosaurs were one such species,
                                                   present in a huge number on this earth millions of

                              Dodo                 years ago. The earth at that time became extremely
                                                   cold and they couldn’t adjust and survive in such
                                                   weather conditions.


                                                   Animals such as tiger, cheetah, Giant Pandas are
                                                   disappearing due to extensive deforestation by
                                                   humans for their selfish needs. Therefore, the number

                                                   of these few animals is on a decline that would soon
                                                   result in their extinction. The animals that are on the
                                     Cheetah
                                                   verge of extintion are called endangered animals.





                                                                                                                    41
                                                                                             Active Science-4]]></page><page Index="35"><![CDATA[Let’s Recapitulate

                  Fill in the blanks with one word.

                  1.  Plant-eating animals are called _____________.
                  2.  Flesh-eating animals are called _____________.

                  3.  Animals who eat plants as well as flesh are called _____________.
                  4.  Animals who are in danger of disappearing are called _____________.
                  5.  Polar bear blends itself with white snow because _____________.



                     LET’S
                    REVISE


                •  Different natural environments where an animal lives are called habitats.

                •  The animals that live on land in different climate conditions are called terrestrial
                   animals.
                •  Aquatic animals are those that live in water.

                •  Snails, lizards and earthworms sleep for a long time in summer to escape heat.

                •  Animals like bear, frog, snakes, etc., sleep for a long time in winter.
                •  Deer, rabbits, mice, etc., can protect themselves from danger because they can run

                   fast.
                •  Animals which are no longer found on the earth are called extinct animals.

                •  Animals that are on the verge of extinction are called endangered animals.




               Let’s Pronounce Together

               hibernation        aerial             arboreal           herbivores         aquatic         camouflage
               extinct            endangered         carnivores         scavengers         omnivores



              Glossary
                   •  Reproduction  :  The process of giving birth to the young ones.

                   •    Aquatic            :  Animals that live in water.
                   •  Amphibians           :  Animals that can live in water and on land.

                   •  Aerial               :  Animals that can fly.
                   •  Host                 :  Animals on which the parasites depend for nutrition.
                   •  Parasite             :  Organisms that live on or inside the other living organism.

                   •  Camouflage           :  Animals that blend with their surroundings.
                   •  Extinct              :  Animals that are unable to adapt to their surroundings.




              42       Active Science-4]]></page><page Index="36"><![CDATA[Practice Time


                A. Tick the correct option.
                1.  Animals that eat only plants are called _____________.

                     a. carnivores                                       b. herbivores
                     c. omnivores                                        d. parasites

                2.  Aquatic animals live in _____________.

                     a. air                                              b. water
                     c. land                                             d. desert

                3.  Animals that can live both on _____________ and in water are called terrestrial
                    amphibians.

                     a. air                                              b. water
                     c. land                                             d. desert

                4.  Are _____________ animals that have fins or limbs which help them to swim.
                     a. fishes                                           b. crocodiles

                     c. frogs                                            d. snakes

                5.  Snails, lizards and earthworms sleep for a long time in summer to escape
                    _____________.
                     a. cold                                             b. preys

                     c. heat                                             d. predators

                6.  Animals that are on the verge of extinction are called _____________ animals.
                     a. endangered                                       b. extinct

                     c. parasitic                                        d. arboreal

                7.  Animals that spend most of their time on/in  _____________ are called arboreal
                    animals.
                     a. plants                                           b. rivers

                     c. trees                                            d. holes

                B. Fill in the blanks.

                1.  _____________ is the means by which animals mix with their surroundings.
                2.  Species that are no longer found on the earth are called _____________.

                3.  The long summer sleep in animals is called _____________.

                4.  _____________ is an arboreal animal and _____________ is an aerial animal.
                5.  The animal on which a parasite depends for nutrition is called _____________.

                6.  Vultures and eagles are _____________ animals.



                                                                                                                    43
                                                                                             Active Science-4]]></page><page Index="37"><![CDATA[C. State whether the following statements are true or false:
                  1.  Frogs can live in water and on land.                                                      ______

                  2.  Animals that eat flesh are called herbivores.                                             ______

                  3.  Bats are aerial animals.                                                                  ______
                  4.  Crows are omnivores.                                                                      ______

                  5.  Mixing with the environment is called camouflage.                                         ______
                  6.  Animals can be divided on the basis of their adaptation.                                  ______

                  7.  Sharp spines of a porcupine protect it from its enemies.                                  ______

                  D. Match the following:

                  1.  Lions                                      a.  terrestrial


                  2.  Fishes                                     b. aestivation


                  3.  Frogs                                      c.  herbivorous


                  4.  Bats                                       d.  desert


                  5.  Tigers                                     e.  carnivorous



                  6.  Camels                                     f.  omnivorous


                  7.  Lizards                                    g.  aquatic


                  8.  Monkeys                                    h.  arboreal


                  9.  Deer                                       i.  amphibians


                10.  Crows                                       j.  aerial

                  E. Look at these animals. Name them and write two adaptive features of

                     each.
                  1.
                                           ________________________________________


                                           ________________________________________



                                           ________________________________________
                  2.
                                           ________________________________________




              44       Active Science-4]]></page><page Index="38"><![CDATA[________________________________________
                3.
                                         ________________________________________




                                         ________________________________________
                4.
                                         ________________________________________


                F. Give two examples of each of the following.

                a.  Aerial animal                                ____________                          ____________
                b.  Aquatic animals                              ____________                          ____________

                 c.  Arboreal animals                            ____________                          ____________
                d.  Amphibians                                   ____________                          ____________

                 e.  Terrestrial animals                         ____________                          ____________
                 f.  He rbivores                                 ____________                          ____________

                g.  Carnivores                                   ____________                          ____________

                h.  Omnivores                                    ____________                          ____________
                 i.  Scavengers                                  ____________                          ____________

                 j.  Endangered animals                          _____________                         ____________

                G. Short Answer Questions.

                1.  Who are endangered animals?
                2.  What is blubber?

                3.  Define arboreal animals.
                4.  What is aestivation?
                5.  Define the following with an example each.

                     a.  Aquatic animals
                     b.  Aerial animals
                     c.  Scavengers

                     d.  Herbivores
                     e.  Extinct animals


                H. Long Answer Questions.
                1.  Describe any five animal adaptations for protection.

                2.  Differentiate between extinct and endangered animals with examples.

                3.  Define camouflaging. Give an appropriate example.



                                                                                                                    45
                                                                                             Active Science-4]]></page><page Index="39"><![CDATA[4.  Distinguish between omnivores and herbivores with examples.
                  5.  Explain the mode of nutrition in parasites. Give examples.




              Think Hard

              Why do arboreal animals need strong muscles?




              Project Work

              Prepare a model showing adaptations of at least four animals.




              Life Skills Activity

                Kids like to break animal homes like a bird’s nest or a beehive. Think is it right to do so?
              Why or why not?




              Research and Development

              There are several animals in the world that are on the verge of extinction. Visit the

              websites of different NGOs, etc., that work to save animal life and prepare a data on how
              many and which animals fall under this category.




              Field Trip

              Suppose you visit a zoo. You get a chance to see different types of animals. Make a list of

              the animals you have seen and their habitats.


                   Net Work

                •  To know interesting animal facts, log on to http://drbenkim.com/amazing-animal-facts.
                   html

                •  For games visit this this site: http://www.sheppardsoftware.com/content/animals/
                   hidden%20animals/Hidden%20Animals.htm

















              46       Active Science-4]]></page><page Index="40"><![CDATA[Circulatory and

                          5                Excretory System












            Learning Objectives


                   To Understand:
                   •  The circulatory system               •  The excretory system


                   To Find Out:
                   •  What are arteries?                   •  About capillaries
                   •  What is urethra?




            Let’s Begin


            The body of living things need energy to work. This energy, they get from food they
            eat. The food after digestion, needs to be carried to all the body parts. The energy
            contained in food reaches to all the body parts by the circulatory system. When the

            body uses energy for various activities, a number of waste products are produced.
            The excetory system removes these wastes from the body.

            Tick the correct box based on whether you can see the body part from

            outside or not.




               1.                Heart                     can see                         cannot see


               2.              Kidneys                     can see                         cannot see


               3.                Brain                     can see                         cannot see


               4.                Eyes                      can see                         cannot see



               5.                Ears                      can see                         cannot see



                                                                                                                     47
                                                                                              Active Science-4]]></page><page Index="41"><![CDATA[C irculatory System

              Our body has many organs which help us to do different things. The circulatory
              system comprises heart, blood and blood vessels which help in transporting the

              substances inside our body.


              Heart
              The heart is about the size of a closed fist. It is located between
              the lungs, a little towards the left side of the body. It is a muscular

              organ which pumps blood, oxygen and other nutrients to every
              little part of the body. It also receives blood from all the organs
              of the body.

                                                        Blood Vessels                                      Heart

                                                        These are thin tube-like structures that form a

                                                        network from the heart through the entire body.
                                                        These tubes carry blood from the heart to all the
                                                        parts of the body and then back to the heart again.
                  Heart                                 The blood vessels are of three types:


                                                            a.  Arteries  : They carry oxygenated blood
                                                                from the heart to all the parts of the body.
                Blood
               Vessels                                      b.  Veins : They carry deoxygenated blood or
                                                                blood with carbon dioxide from different
                                                                parts of the body to the heart.
                 Arteries
                                                            c.  Capillaries  :  Arteries branch out into

                                                                arterioles, i.e., smaller and thinner blood
                    Veins
                                                                vessels. These are  further  grouped  into
                                                                smaller blood vessels called  capillaries.

                                                                Capillaries are the smallest blood vessels
                                                                that help in the exchange of gases, water

                                                                and nutrients between the blood and
                           Circulatory System                   tissues.

              Blood

              Blood is a red-coloured fluid. It flows through blood vessels from the heart to all
              parts of the body and then back to the heart. It transports the nutrients absorbed
              from the food, oxygen, carbon dioxide and water inside the body. It also passes the

              waste produced in the body to the excretory system for removal.


              48       Active Science-4]]></page><page Index="42"><![CDATA[Activity 5.1

            Draw the human circulatory system on a chart and paste it on a thermocol sheet.





            Let’s Recapitulate

                Fill in the blanks.

                1.  ______________ is located between the lungs.
                2.  ______________ carry blood from the heart to all the parts of the body.

                3.  ______________ carry blood from different parts of the body to the heart.

                4.  Arteries branch out into smaller and thinner blood vessels called ______________.



             E xcretory System                                                       Factual Study

            The excretory system helps in the removal of wastes                   It takes about a minute for the
            from our body. Kidneys, ureters, urinary bladder and                  blood pumped by the heart to

            urethra are the main organs of the excretory system.                  go all around our body and get
                                                                                  back to the heart in one go.
            Kidneys

            We have two kidneys in our body. The

            kidneys are bean-shaped. These are present                                                       Kidneys
            just below the ribcage. The kidneys filter
            out the harmful waste, i.e., urine, excreta

            and excess salts from the body.


            Ureters

            Ureters are tube like structures. They act
            as a carrier that carry waste from kidneys                 Ureters
            to the urinary bladder.


            Urinary Bladder

            Urinary bladder is a storehouse of urine                                                         Urinary
                                                                                                             Bladder
            until it is passed out from the body.


            Urethra

            Urethra is a tube that lets out the urine from
            the urinary bladder and out of the body.                                                    Urethra

                                                                                    Excretory System


                                                                                                                    49
                                                                                             Active Science-4]]></page><page Index="43"><![CDATA[Let’s Recapitulate

                  Identify me!

                  1.  I am like a filter that remove waste like urine.                               ______________
                  2.  A am a muscular organ that pumps blood.                                        ______________

                  3.  My job is to remove waste from the body.                                              ______________

                  4.  We are thin tube-like structures in excretory system.                          ______________
                  5.  I am the smallest blood vessel.                                                ______________



                     LET’S
                    REVISE


                •  The circulatory system like heart, blood and vessels help to transport substances
                   inside our body.

                •  The heart is about the size of a closed fist. It is placed between the lungs, a little

                   towards the left side of the body.

                •  Arteries are divided into arterioles and capillaries.

                •  Arteries carry oxygenated blood.
                •  Veins carry deoxygenated blood.

                •  Blood transports nutrients, oxygen, carbon dioxide and water.

                •  Kidneys, ureters, urinary bladder and urethra are organs of the excretory system.

                •  Kidneys filter out harmful waste.






               Let’s Pronounce Together

               circulatory              excretory              veins                   arteries            capillaries
               urethra                  ureter                 urinary bladder




              Glossary

                   •  Circulatory system  :   It helps to transport substances to different parts of the
                                                   body.

                   •    Excretory system         :   It helps to remove waste from the body.







              50       Active Science-4]]></page><page Index="44"><![CDATA[Practice Time

                A. Tick the correct option.

                1.  It is an internal organ.
                     a. heart                                            b. mouth

                     c. nose                                             d. eyes

                2.  It carries blood to all parts of the body from the heart.
                     a. heart                                            b. artery

                     c. vein                                             d. urethra
                3.  It is a red-coloured fluid.

                     a. blood vessels                                    b. blood
                     c. kidney                                           d. urine

                4.  The function of the excretory system is the removal of _____________.

                     a. waste                                            b. blood
                     c. saliva                                           d. water

                5.  Urine passes out from the _____________.

                     a. urethra                                          b. urinary bladder
                     c. kidneys                                          d. heart

                6.  Kidneys are _____________ shaped.
                     a. pencil                                           b. bean

                     c. pea                                              d. square

                B. Fill in the blanks.

                1.  The _____________ pumps blood to all parts of the body.
                2.  Urine flows from the _____________.

                3.  _____________ carry deoxygenated blood.

                4.  Urine gets stored in the _____________.
                5.  _____________ help in the exchange of gases, water and nutrients between the
                    blood and tissues.

                C. Match the following:

                1.  Kidneys                                    a.  red fluid

                2.  Blood                                      b.  bean-shaped


                3.  Heart                                      c.  a pair of tubes

                4.  Ureters                                    d.  located between the lungs



                                                                                                                    51
                                                                                             Active Science-4]]></page><page Index="45"><![CDATA[D. Short Answer Questions.
                  1.  What is the function of heart?

                  2.  Name the organs of the excretory system.
                  3.  What is the function of kidneys?

                  4.  Write the name of blood vessels.

                  E. Long Answers Questions.

                  1.  Describe the circulatory system.

                  2.  Describe the excretory system with labelled diagram.

                  F. Label the given diagrams.

                  a.  Circulatory system
                  b.  Excretory system





































              Think Hard

              Anne’s father has some heart problem. Which of the following foods would help him to

              keep his heart healthy. Thick () and write the name of given foods he should eat.
















              52       Active Science-4]]></page><page Index="46"><![CDATA[Project Work
            Make a chart on the games which you play. List any three of them that you think help to

            keep you healthy and strong. Also, write how they help you.




            Life Skills Activity

            Hina regularly goes to a park with her grandmother. There she plays football and does
            yoga. While returning home, she feels tempted to buy snacks from the street vendor.

            Should she eat them? Why or why not?




            Research and Development

            What do you understand by heart attack? Find out about it.




            Field Trip

            Plan a visit to a farm and note the viviparous and oviparous animals housed there.



                 Net Work

              •  To see the facts on human body log on to http://icantseeyou.typepad.com/

                 my_weblog/2008/02/100-very-cool-f.html



















                                                                                                                    53
                                                                                             Active Science-4]]></page><page Index="47"><![CDATA[6        Food: Our Basic Need












              Learning Objectives


                     To Understand:
                     •  Food groups                                        •  Balanced diet
                     •  Need to cook and preserve food                     •  Regular exercise to stay healthy



                     To Find Out:
                     •  Various nutrients present in food                  •  About different types of food

                     •  What is roughage?




              Let’s Begin

              Identify different food items which make us fat. Write J against junk food
              and H against healthy foods.





































             54       Active Science-4]]></page><page Index="48"><![CDATA[W hy Do We Eat Food?

            Every human being is busy in doing one thing or the other like running, driving,
            eating, playing, etc. Therefore, we all need a lot of energy for survival.


            Food gives us energy to work. It also keeps us healthy and disease-free.  So, we
            should eat healthy food to stay fit.



             F ood Groups


            Nutrients are the substances that are present in our food. These substances keep
            us healthy, help in body’s growth and make us strong. Carbohydrates proteins,
            fats, vitamins and minerals are the main nutrients that are present in our food.

            Roughage and water are also present in our food. These also play an important
            role in our body.

            Food is grouped into three categories according to the nutrients present in them.

                 •  Energy-giving food
                 •  Protective food

                 •  Body-building food


                                                               Carbohydrates

                                                               Foods which are rich in carbohydrates

                                                               are called  energy-giving foods. There
                                                               are two types of carbohydrates – sugar
                                                               and starch. Food that contains starch are

                                                               wheat, rice, potato, sweet potato, bread,
                                                               etc. Pastries and ice creams contain a lot
                                        Carbohydrates          of sugar. Athletes and labourers need more

            carbohydrates than the people who do sitting jobs. Because the people who do
            more physical work need more energy for  their everyday activities.


            Fats

            Fats are also energy–giving foods. They
            give us more energy than carbohydrates.

            Oil, ghee, cream, cheese, paneer, etc., are
            foods which contain fats. We should not eat
            too much fat because excess fat is deposited

            in our body which makes us obese.                                        Fats


                                                                                                                    55
                                                                                             Active Science-4]]></page><page Index="49"><![CDATA[Proteins
                                                                                   Factual Study
              Food which is rich in protein is called body–                     •  Broccoli contains twice the
              building food. Proteins help us to grow and                          vitamin C present in an orange.

              repair the worn-out tissues and cells. Children
              need more proteins than adults. Eggs, pulses,                     •  Fresh beans contain vitamin A,

              meat and milk are examples of such food.                             vitamin B-complex, calcium and
                                                                                   potassium.











                               Pulses                                            Meat

              Vitamins And Minerals
                                                                                                        Eggs
              Food which contains vitamins and
              minerals are called  protective

              food because they protect us from
              diseases.Vitamins and minerals keep

              us healthy. Fresh fruits, vegetables,
              milk and cereals are some examples
              of foods containing vitamins.


              Iron and calcium are minerals which                               Cereals
              keep us healthy and strong. Calcium
              keeps our teeth and bones strong.                                                                Milk

              Iron keeps us energetic and strong.
              So,  we should eat  vegetables,  fruits,
              eggs, fish, milk and cereals. Our body

              needs vitamins and minerals in a very
              small quantity.


              Roughage And Water                                             Fruits and Vegetables

              Roughage means fibre. Raw fruits and vegetables; cereals have fibre in them.
              Roughage does not provide any nutrient but it helps in the proper functioning of

              the digestive system. It enhances the movement of food through the intestine and
              easy removal of waste. Water is a very important part of life. It maintains our body
              temperature  and helps in digestion. We lose water by means of urine, sweat and

              breath, so, we should drink plenty of water every day.


              56       Active Science-4]]></page><page Index="50"><![CDATA[Activity 6.1

            Fill in the food items that provide the respective nutrient.



               Carbohydrates          Proteins           Fats          Vitamins         Minerals        Roughage

























             B alanced Diet

            A balanced diet contains all the nutrients like
            carbohydrates, proteins, fats, vitamins, minerals,

            water and roughage in the right quantity and right
            proportion. It is very important in order to stay

            healthy.

                                                                                            Balanced Diet
            Let’s Recapitulate

                Fill in the blanks.

                1.  Food which gives us energy is called _____________.
                2.  Fat is _____________ giving food.

                3.  Wheat, rice and potato contain _____________.
                4.  Proteins help in _____________.

                5.  Eggs, meat, pulses are a rich source of _____________.



             P reservation Of Food

            Preservation of food is very important. If food is exposed to air or moisture for a

            long time, it would get spoiled; whether cooked or uncooked. The methods use to
            preserve food for a long time are called food preservation. There are lots of ways
            to keep cooked and uncooked food preserved.



                                                                                                                    57
                                                                                             Active Science-4]]></page><page Index="51"><![CDATA[1.  Refrigerating: Food can be preserved
                                                                        by keeping fruits, vegetables and

                                                                        cooked food in the fridge. Refrigerator
                                                                        keeps the food fresh.


                                                Drying             2.  Drying: Drying the food items will
                                                                        save it from getting spoilt. Drying is
                                                                        one of the easiest methods to prevent
                                                                        food from spoiling. Dry fruits like

                                                                        dates, raisins can be kept in the open
                Refrigerating
                                                                        under the sun. Papads are also made

                                                   Jellying             by drying.

                                                                   3.  Canning: Air and moisture can spoil
                                                                        food. To protect food from moisture,
                                                                        store it in the air tight containers.

                                                                        For example, rasogullas, vegetables,
                                                                        biscuits, etc.


                         Canning                                   4.  Pickling:  Germs cannot survive
                                                                        in the concentrated solution of salt
                                                                        and oil. Therefore, pickles can be
                                                                        preserved easily. Seasonal fruits and

                                                                        vegetables like mango, turnip, carrot,
                                                                        cauliflower, etc., are preserved by
                                        Pickling                        pickling.


                  5.   Jellying: To preserve fruit and vegetables, they are put in sugar syrup.
                       Sugar is also a strong preservative as it retards the growth of germs.




               R est, Posture And Exercise

              Along with a balanced diet, sufficient rest, regular exercise and an appropriate
              body posture are some other relevant factors that help us to keep healthy.


              Rest

              Rest is a major prerequisite to stay fit. If we
              do not take proper rest, we will fall sick and

              feel tired always. Therefore, a 6 to 8 hour
              sleep every day is essential for everyone.



              58       Active Science-4]]></page><page Index="52"><![CDATA[Posture

            Body posture plays an important role in keeping us fit.
            Every person has a different posture while sitting, walking,

            standing, etc. Correct posture helps us in many ways:

                 1.  Gives us a good appearance.

                 2.  We do not get tired quickly.

                 3.  Our muscles and joints can be used properly.


                 4.  We don’t feel pain, especially in the back and neck.


            Exercise
            Exercise is very important for human body. It keeps us healthy and fit. There are

            different types of exercises like cycling, playing, running, walking and yoga which
            help us in many ways. Regular exercise helps in:


                 1.  Proper sleep

                 2.  Maintaining body weight

                 3.  Energising the body

                 4.  Providing relief from tiredness.




            Let’s Recapitulate

                A. Define.

                     1.  Food preservation                            2. Balanced diet
                     3.  Nutrients


                B. State whether the following statements are true or false:
                    1.  Fats are body-building food.                                                      ______

                    2.  Proteins are energy-giving food.                                                  ______
                     3.  Breathing leads to water loss in the body.                                       ______

                     4.  Jellying is one of the methods to preserve food.                                 ______
                     5.  Exercise is not important to stay fit.                                           ______




              Let’s Pronounce Together


              carbohydrates           minerals                proteins               exercise
              preservation            nutrients               vitamins

                                                                                                                    59
                                                                                             Active Science-4]]></page><page Index="53"><![CDATA[LET’S
                    REVISE



                •  Food is essential for us.
                •  We need food for energy, growth and survival.

                •  Nutrients present in food keep us healthy, help the body to grow and make us strong.

                •  Fats give us more energy than carbohydrates.
                •  Roughage is fibre. Raw fruits, vegetables and cereals are fibre-rich foods.

                •  Refrigeration, drying, canning and pickling are the various means of food preservations.
                •  Exercise, rest and body posture are very important to keep us healthy.



              Glossary

                   •  Nutrients           :  Substances present in food which keep us healthy and strong.

                   •  Roughage            :  Fibre-rich food.
                   •  Balanced diet  :  A diet that contains all nutrients in the right proportion.

                   •  Preservation  :  Method to keep food fresh and prevent it from getting spoilt.




              Practice Time

              A. Tick the correct option.

                  1.  Carbohydrates are known as ______________.
                      a. energy-giving food                                b. body-building food

                      c. protective food                                   d. roughage
                  2.  Fresh fruit and milk are the source of ______________.

                      a. vitamins                                          b. proteins
                      c. carbohydrates                                     d. fats

                  3.  Calcium makes ______________.
                      a. bones strong                                      b. eyes strong

                      c. muscles strong                                    d. blood thicker

                  4.  Jellying is a method of preserving food by ______________.
                      a. adding sugar                                      b. adding salt
                      c. removing water                                    d. freezing


              B. Fill in the blanks.
                  1.  Carbohydrates and fats provide us _____________.

                  2.  Vitamins and minerals protect our body from _____________.


              60       Active Science-4]]></page><page Index="54"><![CDATA[3.  Egg, fish, meat and pulses are rich in _____________.
                4.  The process to prevent food from getting spoilt is called _____________.

                5.  Presence of all the nutrients in a meal is called a _____________.
                6.  Our body needs at least _____________ of sleep.


            C. Match the following:
                1.  Proteins                                   a. energy-giving food


                2.  Carbohydrates                              b. strong teeth, bones

                3.  Calcium                                    c. body-building food

                4.  Iron                                       d. makes food last longer


                5.  Preservation                               e. apples

            D. Give three examples of foods that are rich in

                1.  Carbohydrate                  ____________             ____________              ____________
                2.  Protein                       ____________             ____________              ____________

                3.  Fat                           ____________             ____________              ____________

                4.  Roughage                      ____________             ____________              ____________

            E. Write E for energy giving, B for body building and P for protective food.



















            F. Short Answer Questions.

                1.  Why is a balanced diet important for us?
                2.  What are nutrients?

                3.  What are energy-giving food?

                4.  What is the role of water in our diet?
                5.  What are proteins?

            G. Long Answer Questions.

                1.  Why is exercise important for our body?

                2.  Explain the different ways of preserving food.

                                                                                                                    61
                                                                                             Active Science-4]]></page><page Index="55"><![CDATA[3.  Name different types of nutrients with examples.
                  4.  Explain vitamins and minerals.

                  5.  What is a balanced diet?
                  6.  Why the people doing more physical activity need lots of carbohydrates?

                  7.  What are the benefits of an appropriate posture?




              Think Hard

              Meena suffers from stomachache quite often. What could be the reason?




              Project Work

              Prepare a dish which has at least four nutrients in it. Also write in what quantity you
              should take the ingredient. Take help of your mother or elders.




              Life Skills Activity

              Thousands of children around the world do not get proper food in a day.

               1.  Do you think one should waste food?

               2.  Have you ever reused the left-over food from a party? If not, what do you do with it?




              Research and Development

              Malnutrition is prevalent in many countries of the world. Search the internet or ask people
              about the extent of malnutrition and the steps taken by the government to eradicate it.

              For example, Akshaya Patra Mid-day Meal Programme very good step towards it.




              Field Trip

              Visit a local dhabha or a restaurant. Request the manager to allow you into the kitchen.
              What  cleanliness and hygiene standards do you observe?




                   Net Work

                •  To know interesting facts about Indian food, log on to http://www.scoopwhoop.com/
                   inothernews/food-fact-2/

                •  To attempt a quiz on food, log on to http://www.sciencekids.co.nz/quizzes/food.html




              62       Active Science-4]]></page><page Index="56"><![CDATA[Digestion of Food

                          7












            Learning Objectives


                   To Understand:
                   •  Role of teeth in digestion of food              •  Digestive system
                   •  Microbes



                   To Find Out:
                   •  What are milk teeth?                            •  How the food gets digested?




            Let’s Begin


            The proper digestion of food is necessary to release energy from it. In the body, there
            are various organs involved in the digestion of food. Teeth also play important role
            in this process.


            Given below are some pictures. Discuss how these actions impact our teeth.



















             T eeth

            Teeth play a crucial role in keeping us fit. Healthy teeth would lead to healthy
            eating. Teeth help us in chewing and biting the food. They help us while speaking.

            A baby starts developing teeth at the age of six months. These teeth are twenty in
            number and are called milk teeth.


                                                                                                                     63
                                                                                              Active Science-4]]></page><page Index="57"><![CDATA[Milk teeth are also known by temporary teeth. These

              teeth start falling one by one between the age of 6 and
              12. Thereafter, a new set of teeth starts developing

              in their place. This set has about 32 teeth, 16 in the
              upper jaw and 16 in the lower jaw. This set of teeth

              is known as permanent teeth. It lasts long until the
              old age.



              Structure Of Teeth

              Teeth are held in the socket of the pink-coloured gums.
              There are three parts of a tooth.                                             Temporary Teeth

                  •  Crown  : The part above the gum which is

                       visible is called the crown.

                  •  Neck   :  The part which is below the crown, touching the gum is called the

                                    neck.

                  •  Root   : The part of the tooth inside the gum is known as the root.


              Enamel is the hardest part of
              the body. It is the hard outer                                                            Enamel

              covering of the tooth which is                                                            Dentine
              white in colour.                           Crown  (above gum)


              The layer below the enamel                                                                Gum
              is called  dentine. There is                                                              Pulp cavity
              pulp below the dentine. The                   Neck                                        Tough fibres

              soft part of the tooth is called
              the  pulp. It is connected to                                                             Cement

              the gum through a hole in the                                                             Nerve
              root. There are blood vessels              Root  (embedded in bone)                       Blood vessels
              and nerves inside it.                                                                     Jaw bone




                                                                       Structure of tooth
              Types Of Teeth
              There are four types of teeth in the permanent set – incisors, canines, premolars

              and molars.




              64       Active Science-4]]></page><page Index="58"><![CDATA[Gum










                    Molars
                                                           Incisors         Canines        Premolars          Molars


                 Premolars
                Canine
                   Incisors
                             Permanent Teeth
                 •  Incisors : Incisors help in cutting and biting the food. The front four teeth
                     in both the jaws are incisors, i.e., four in upper jaw and four in lower jaw.

                 •  Canines : Canines help in holding and tearing the food. They are on the
                     either side of incisors. There a are of total four canines – two in the upper

                     jaw and two in the lower jaw. Carnivores tear flesh easily due to the presence
                     of strong and sharp canines.
                 •  Premolars : Premolars help in crushing and grinding the food. These are

                     placed next to the canines. There are four premolars in each jaw. These
                     teeth are usually broader than the other teeth.

                 •  Molars : Molars are used for chewing and grinding the hard food items.
                     These are placed at the end of the mouth. There are 12 molars – six in each
                     jaw. They are bigger and broader. These teeth grow at different stages.


            Care Of Teeth
            Tiny particles of food that remain stuck in the teeth while eating, can cause the
            growth of bacteria. If these germs are not removed, they will create a sticky coating
            called plaque on the enamel layer. The bacteria further attack the dentine and
            lastly the pulp.This way the germs reach deep into nerve area of tooth leading to

            severe toothache.

            If we take care of our teeth, we can save them from decaying. There are a few ways
            by which we can keep our teeth healthy and clean.

                 1.  Brush your teeth twice a day, i.e., in the morning
                     as well as at night before going to bed. Upward
                     and downward movement of the toothbrush in a
                     circular motion is the proper way for brushing.

                 2.  Rinse your teeth after every meal. Gargle would
                     be an added safety measure.



                                                                                                                    65
                                                                                             Active Science-4]]></page><page Index="59"><![CDATA[3.  Use dental floss or mouthwash.

                  4.  Eat lots of fruit and salad rich in vitamin C.

                  5.  Avoid junk food, sweets and chocolates.

                  6.  Eat calcium rich food like cheese, eggs, milk, etc.


                  7.  Visit a dentist regularly.



              Let’s Recapitulate

                  Fill in the blanks.

                  1.  The first set of teeth is called ______________.

                  2.  The visible part of the tooth above the gums is called ______________.
                  3.  The layer below the enamel is called ______________.

                  4.  The part of the tooth inside the gum is called ______________.
                  5.   ______________ is the soft part of the tooth.




               D igestive System

              Food gives energy to our body. But we get  Mouth
              this energy only, if the food which we eat
              breaks down into small particles, so that                 Salivary

              it can be easily absorbed by the body. This                gland
              process is called digestion.

              There are different organs in our body which             Mouth                            Liver

              help in the digestion of food. These organs                                               Stomach
              together form the digestive system.
                                                                                                        Pancreas

              Process Of Digestion                                                                      Small Intestine

              When we put food into our mouth, the                                                      Large Intestine
              digestive system starts working from that                                                      Rectum
                                                                                                              Anus
              moment. When we start chewing, the
              saliva mixes with the food.  Saliva is the
              digestive liquid secreted by the salivary                        Digestive System

              glands present in mouth. Saliva makes the food soft and moist. It is now known as
              bolus and can be easily swalowed. The food that contains sugar, is broken down into
              glucose by the saliva and hence, it tastes sweet. Rice is one such example.





              66       Active Science-4]]></page><page Index="60"><![CDATA[The food or bolus then goes into the stomach through the food pipe. The food pipe
            contracts and relaxes so as to push the food down into the stomach. The stomach

            is a muscular bag where food stays for many hours. It produces digestive juices
            and acid which help to digest the food.

            The remaining undigested food is pushed into a long coiled tube called the small

            intestine. The small intestine, along with the liver and pancreas produces a juice
            that mixes with the food and digests it. The walls of the intestine absorb all the
            nutrients from the digested food. Then the blood vessels which carry digested food

            absorb these nutrients and transport them to all parts of the body.

            Undigested food passes into the  large intestine  where the extra water and
            minerals are absorbed. The  rectum stores the remaining solid waste until it

            passes out through the anus.

            Activity 7.1


            Find out why your stomach produces a rumbling sound in between meals.



            Let’s Recapitulate

                Fill in the blanks.

                1.  The process of breaking down of food into a simpler form is called _____________.

                2.  _____________ is a digestive liquid secreted by the salivary glands.
                3.  The undigested food pushed into a long tube is called _____________.

                4.  The extra water is absorbed by _____________.
                5.  The food stays in the stomach for _____________.




             M icrobes

            We cannot see microbes with naked eyes. Microbes can only be seen through a
            microscope because they are very tiny in size. They can grow anywhere – on or
            inside our body, on soil, food, stagnant water, etc. Microbes which cause diseases

            are called germs or pathogens.

            There are four kinds of microbes.


            Bacteria

            Bacteria (sing. bacterium) are made up of single cell. They can be
            rod-shaped, spiral or round in shape. Bacteria can cause many
            diseases like typhoid, tuberculosis and pneumonia.                                           Bacteria


                                                                                                                    67
                                                                                             Active Science-4]]></page><page Index="61"><![CDATA[Viruses

              These are the smallest living beings. Therefore, these can
              be seen under a very powerful microscope only. Viruses
              can cause many diseases like chicken pox, dengue,

              mumps, cold, etc.
                                                                                           Virus
              Fungi

              Fungi (sing. fungus) grow on dead or rotten matter. These
              can cause skin disease like ringworms and candidiasis.
                                                                                                             Fungi
              Protozoa

              Protozoa (sing. protozoan) are single-celled microbes.
              These can cause diseases like dysentery and malaria.

                                                                                                             Protozoa
              Useful Microbes
              Some microbes are useful in following ways:


                  1.  Bacterium lactobacillus helps in making curd. It also helps in breaking down
                       of dead and decaying matter.

                  2.  Some bacteria help in the digestion of the food we eat.

                  3.  Some bacteria and viruses are useful in obtaining medicines.


                  4.  Protozoa are very useful in making the soil fertile.

                  5.  Some fungi like yeast are very useful in making the bread soft.



              Let’s Recapitulate

                  Match the following:

                  1.  Bacteria                                   a. candidiasis
                  2.  Fungi                                      b. dysentery

                  3.  Virus                                      c. typhoid

                  4.  Protozoa                                   d. chicken pox


                     LET’S
                   REVISE


                •  A baby starts developing teeth at the age of six months.

                •  The tooth has three main parts – crown, neck and root.


              68       Active Science-4]]></page><page Index="62"><![CDATA[•  Enamel is the hardest part of the body.

              •  Humans have two sets of teeth – the milk teeth and the permanent teeth.
              •  Milk teeth start falling between the age of 6 and 12 and permanent teeth start
                 growing in their place.

              •  Measures like brushing, gargling, avoiding junk food, sweets and chocolates, eating
                 healthy food, fruits, green vegetables, regular dental visit, etc., must be taken to
                 protect your teeth from germs.

              •  Calcium and vitamin C are very important for healthy and strong teeth.
              •  While eating food, little particles of food that remain stuck on the teeth can cause the
                 growth of bacteria.

              •  When we put food into our mouth, the digestive system starts working from that
                 very moment.
              •  We cannot see microbes with naked eyes. They can be seen using a microscope

                 because they are very tiny in size.
              •  Different microbes cause different diseases like typhoid, chicken pox, candidiasis, etc.
              •  Useful microbes help in preparing various food items and medicines.




              Let’s Pronounce Together


              dentine                 enamel                  fungi                  microbes              saliva
              canine                  protozoa                intestine              pancreas






            Glossary

                 •  Crown         :  The tooth above the gum which is visible.

                 •  Neck          :   The part which is below the crown, touching the gum.
                 •  Root          :   The part of the tooth inside the gum.
                 •    Enamel      :   The hard outer covering of the tooth which is white in colour.

                 •  Dentine  :   The layer below the enamel.
                 •    Saliva      :   It is a digestive juice secreted in the mouth.

                 •    Digestion :   Breaking down of food into small particles so that it can be easily
                                    absorbed by the body.

                 •    Protozoa  :   Single-celled microbes.
                 •    Microbes  :   Tiny living things.

                 •    Fungi       :   These grow on dead and rotten matter.






                                                                                                                    69
                                                                                             Active Science-4]]></page><page Index="63"><![CDATA[Practice Time

                  A. Tick the correct option.

                  1.  The part of the tooth inside the gum is called _____________.
                      a. root                                              b. crown

                      c. enamel                                            d. pulp
                  2.  They help in cutting and biting and are placed in front of the jaw.

                      a. Incisors                                          b. Canines
                      c. Molars                                            d. Premolars

                  3.  There are _____________ sets of teeth in humans.
                      a. four                                              b. two

                      c. three                                             d. one
                  4.  The milk teeth fall off by the age of _____________.

                      a. four                                              b. six
                      c. seven                                             d. thirteen

                  5.  _____________ is one of the organs of the digestive system.
                      a. Liver                                             b. Pancreas
                      c. Large intestine                                   d. All the above

                  6.  Our mouth is connected to our stomach through the _____________.

                      a. intestine                                         b. food pipe
                      c. liver                                             d. none of the above
                  7.  _____________ are very tiny living beings.

                      a. Microbes                                          b. Teeth

                      c. Rats                                              d. None of these

                  B. Fill in the blanks.
                  1.  ______________ is the upper part of the tooth, above the gum, which is visible.

                  2.  The first set of the teeth is called ______________.
                  3.  Breaking down of food into small particles so that it can be easily absorbed by the
                      body is called ______________.

                  4.  Malaria is caused by ______________.
                  5.  Ringworms are caused by ______________.

                  6.  Disease causing microbes are called ______________.
                  7.  The part of the tooth that has blood vessels and nerves is called ______________.

                  8.  It is the hardest outer part of the teeth is called ______________.
                  9.  Visit a ______________ regularly to know how healthy your teeth are.

                10.   The undigested food enters the ______________.

              70       Active Science-4]]></page><page Index="64"><![CDATA[C. Match the following:
                1.  Dentine                                    b. ringworms

                2.  Enamel                                     c. storehouse of solid waste
                3.  Molars                                     d. malaria

                4.  Bacteria                                   f. hardest part of our body

                5.  Fungus                                     g. tetanus
                6.  Viruses                                    h. dengue, chickenpox

                7.  Protozoa                                   i. 12 in number
                8.  Rectum                                     j. layer below the enamel


                D. Label the diagrams given below.
                1.  Structure of the tooth                                   2.  Digestive System






























                E. Short Answer Questions.

                1.  How are teeth important to us?
                2.  What are microbes?

                3.  Name two diseases caused by fungus.
                4.  Name the different parts of a tooth.

                5.  How do microbes useful to us? Write one example.

                F.  Long Answer Questions.

                1.  Why should we keep our teeth clean?
                2.  What type of food is good for teeth?

                3.  How can we take care of our teeth?
                4.  Explain four kinds of microbes.



                                                                                                                    71
                                                                                             Active Science-4]]></page><page Index="65"><![CDATA[Think Hard

              Ankita’s father has weak teeth. How can he make his teeth strong?




              Project Work

               1.  Draw the upper and lower jaw and colour it. Also write down its parts and usage.

               2.  Visit your school biology lab. Your teacher will show you the different parts of the
                   digestive system. Try and draw it in your notebook.




              Life Skills Activity

              Prepare a meal plan for a 6-month old baby with no teeth and a 72 year old person with
              no teeth. Do you find any similarity?





              Research and Development
              Find out why milk teeth fall so early? Take help of internet.





              Field Trip
              Visit  a dentist and  ask  him to  show  your different  parts  of teeth and  explain their

              functions. Next day, discuss the points in class.



                   Net Work

                •  To play different games on teeth, log on to http://www.colgate.com/en/us/kids/kids-corner

                •  To know more about digestive system, log on to http://www.sheppardsoftware.com/health/
                   anatomy/digestion/digestion_tutorial.htm

























              72       Active Science-4]]></page><page Index="66"><![CDATA[Clothes

                          8












            Learning Objectives


                   To Understand:
                   •  Need for clothes                     •  Fibres and fabrics
                   •  Care of clothes



                   To Find Out:
                   •  About natural fibres                 •  Samples of different type of clothes




            Let’s Begin


            Clothes are essential for us like food and shelter. These are our basic necessity. We
            all like to wear good clothes.

            Match the clothes to the correct cloud.





                 Worn by                                               Worn by men                Worn by men
              women only                  Worn by girls                 and women                       only
                                                                             both

























                                                                                                                     73
                                                                                              Active Science-4]]></page><page Index="67"><![CDATA[N eed For Clothes

              Clothes protect us from adverse weather conditions like
              storm, heat, cold, rain, dust, etc., and also from animal and

              insect bites. Clothes also give us a smart appearance.

              In ancient time, humans used to cover their bodies with
              leaves or skin of dead animals. But as the time passed, they

                                  learnt how to weave and stitch clothes. Now,
                                    clothes for different places and activities
                                     are available in the market. For example,

                                       clothes for playing, party, school, home
                                        sleeping, etc.



                                        Activity 8.1

                                        Write the names of your and your friend’s favourite dresses here.

                                         ____________________________________________________________
                                       ____________________________________________________________



                  1.  In summers, we wear clothes made of cotton. They absorb sweat. Light
                       coloured and white clothes are best suited for hot weather because they

                       reflect heat and keep the body cool.

                  2.  In winters, we wear woollen clothes to keep our body warm. It protects us
                       from cold.


                  3.  In rainy days, we wear raincoat, made of waterproof material.  It protects
                       us from rain. Raincoats are wrinkle-free and also dry up easily.













              Clothes in Winter
                                                                           Clothes worn
                                                                             in Punjab






                                            Rainy Season Clothes                                 Professional Clothes


              74       Active Science-4]]></page><page Index="68"><![CDATA[4.  People who live in different places wear different types of clothes, according
                     to their tradition.The clothes of a person living in Punjab will be different

                     from that of a person living in Tamil Nadu.

                 5.  Some people wear some special clothes for specific work. These are called
                     uniforms. The uniforms  tell the profession of the persons. Examples are

                     postmen, lawyer, doctor, soldier, nurse, etc.



             F ibres And Fabrics

            Fabric is a woven or knitted cloth using
            long hair-like threads called fibres. It can

            be natural or synthetic. Fabric is stitched
            to make clothes.                                                 Sheep                 Woollen Sweater


            Natural Fibres

            Fibres which are obtained from plants and
            animals are called natural fibres.

            Example: wool from sheep, jute, linen and

            cotton from plants and silk from silkworm.

                                                                                Jute Plant
                                                                                                         Jute bag








                   Cotton Plant






                                                                 Silkworm                           Silk Saree
                         Cotton Shirt
            Synthetic Or Man-made Fibres

            Fibre made by man, i.e., which is not natural is called
            synthetic  or  manmade  fibre. Some examples of
            synthetic fibres are nylon, polyester, rayon, terylene.

            They never fade and last long. They can be stretched
            easily, i.e., they are strong enough. They are waterproof

            and wrinkle-free.
                                                                                             Synthetic Dress


                                                                                                                    75
                                                                                             Active Science-4]]></page><page Index="69"><![CDATA[Let’s Recapitulate
                                                                                       1
                  Read the clues and solve the crossword.

                      ACROSS
                  2.  We wear these inside the shoes                                            3

                  4.  This is made of denim                              2

                  6.  Little girls wear this
                      DOWN                                                                                5

                  1.  We usually wear this in winter
                  3.  Mummy wears it for the party
                                                                                       4
                  5.  Children wear it in school






                                                                                            6











               C are of Clothes

              Clothes need good care. We should know from which material our clothes are made
              and how to take care of them. Some important measures are:

                  1.  To remove dirt, stains and sweat, we should wash the clothes properly with
                       soap or detergent. Clean clothes are hygienic and help us stay healthy.

                  2.  Clothes should be properly dried after washing.
                  3.  We should iron the clothes after drying as they might have got wrinkled.

                  4.  We should not soak silk and woollen clothes in hot water. Silk and woollen
                       clothes should be washed gently. These clothes can be dry-cleaned or dried
                       under mild sunlight.

                  5.  Clothes should be stored properly when not in use. The silk and woollen
                       clothes may be attacked by insects like moths and silverfish if not stored
                       properly.

                  6.  We should use neem leaves and naphthalene balls to keep silk and woollen
                       clothes safe from insects.

                  7.  Stored clothes should be taken out and dried under the sun for a while to

                       remove any smell in them.


              76       Active Science-4]]></page><page Index="70"><![CDATA[LET’S
                  REVISE


              •  Clothes are our basic needs like food and water.

              •  We need clothes to protect ourselves from rain, heat and cold weather.
              •  Clothes are made from different types of material like cotton, silk, etc.

              •  People from different regions wear different types of clothes.
              •  Fibres which are made by man are called synthetic fibres.

              •  Fibres are long and hair-like threads that can be woven or knitted into a fabric. They
                 can be natural or synthetic.




              Let’s Pronounce Together

              wrinkle-free            fabric                  synthetic              weaving             knitting




            Glossary

                 •  Fibre                 :     Long hair-like thread from which fabric is made.

                 •    Natural fibre     :       Fibre which is obtained from plants and animals.
                 •    Manmade fibre :           Fibre that is not found in nature, which is man made.

                 •  Fabric                :     Material used for making clothes.





            Practice Time
                A. Tick the correct option.

                1.  In summers, we wear clothes made of _____________.
                     a. cotton                                           b. silk

                     c. rubber                                           d. wool
                2.  A _____________ is a woven or a knitted cloth with long hair-like threads.

                     a. fibre                                            b. fabric
                     c. cloth                                            d. silk

                3.  Fibre which is made by humans are called _____________.
                     a. silk                                             b. linen

                     c. polyester                                        d. synthetic
                4.  Clothes should be properly _____________ after washing.

                     a. ironed                                           b. dried
                     c. burnt                                            d. worn


                                                                                                                    77
                                                                                             Active Science-4]]></page><page Index="71"><![CDATA[B. Fill in the blanks.
                  1.  We wear _____________ clothes in summer.

                  2.  The students of school wear _____________.
                  3.  We wear _____________ at bed time.

                  4.  Clothes are something that we need to _____________ daily.

                  5.  The material used for making clothes is known as _____________.
                  6.  Silk is a _____________ fibre.


                  C. State whether the following statements are true or false:
                  1.  We wear night dress to school.                                                            ______

                  2.  Fibre which is made by man is called natural fibre.                                       ______

                  3.  Silk is made by silkworms.                                                                ______
                  4.  Sheep give us wool.                                                                       ______

                  5.  We should wear dirty clothes.                                                             ______
                  6.  Nylon and polyester are synthetic fibres.                                                 ______


                  D. Match the following:

                  1.  Fibre                                      a. from plants

                  2.  Naphthalene balls                          b. from silkworms


                  3.  Winters                                    c. protect from insects

                  4.  Silk                                       d. raincoat

                  5.  Jute                                       e. hair-like thread


                  6.  Summers                                    f. leaves and skin of animals

                  7.  Rains                                      g. cotton clothes

                  8.  Early humans                               h. woollen clothes


                  E. Identify and label these pictures.
                  1.                                                     2.


















              78       Active Science-4]]></page><page Index="72"><![CDATA[3.












                F. Short Answers Questions.

                1.  What is a natural fibre?

                2.  Write the names of five different types of clothes.
                3.  What is a fabric?

                4.  Why do we need clothes?
                5.  Early man used to wear leaves and skin of dead animals. Do you think they were
                    safe?


                G. Long Answere Questions.
                1.  How should we take care of clothes?

                2.  Name two types of fabric. Give examples.
                3.  How did early man protect himself?

                4.  Write about seasonal clothes.
                5.  Why do silk and woollen clothes need extra care?





            Think Hard
            Azim usually wears woollen clothes. Which of the following places is he more likely to

            live in?

                a. Punjab                    b. Kashmir                     c. Chennai                  d. Shimla

            What will happen if he will wear cotton clothes in these places?




            Project Work
            Draw different types of clothes and colour them in your scrapbook.





            Life Skills Activity
            What do you do with your old or discarded clothes? Donating old clothes to the poor is a

            good deed. However, do you think that we should donate torn and ragged clothes? Why
            or why not?



                                                                                                                    79
                                                                                             Active Science-4]]></page><page Index="73"><![CDATA[Research and Development

              Your mother puts a packet of naphthalene balls in the suitcase containing woollen clothes.
              When she opens the suitcase in the next winters, she keeps all those clothes under mild
              sunlight for a few hours. Why? What will happen if she will not put naphthalene balls

              in the suitcase?




              Field Trip

              We often see cloth merchants in local market. Visit such a shop to learn the names of
              different fabrics and collect their samples.




                   Net Work

                •  For a fun activity, log on to http://www.eslkidstuff.com/esl-kids-games/clothes-games.
                   htm#.VYTvlvljL_g

                •  For games associated with clothes, log on to http://www.themagiccrayons.com/games/
                   clothes/

















































              80       Active Science-4]]></page><page Index="74"><![CDATA[Air, Water and

                          9
                                                       Weather











            Learning Objectives


                   To Understand:
                   •  The sun and the weather                            •  Air
                   •  Water



                   To Find Out:
                   •  About filtration                                   •  What is chlorination?

                   •  Why do we have seasons?




            Let’s Begin

            Identify the pictures and find out the words related to the environment.







































                                                                                                                     81
                                                                                              Active Science-4]]></page><page Index="75"><![CDATA[T he Sun And The Weather

              The sun is a huge ball of fire. It causes the change in the weather. The condition
              of atmosphere around us at a specific time is called weather. The weather can

              be hot, cold, windy, dry or humid. The weather is different everywhere. The place
              where you live can be hot, in other places it may be cloudy or snowy. It is also
              possible that when you go to school in the morning, it might be sunny but on
              your way back home, it can be rainy. The main factors responsible for weather

              change are movement of air and change in the form of water. Both the factors are
              influenced by the heat of sun.


              What Causes Day And Night?

              The earth rotates around the sun.
              It takes 24 hours to complete one
              rotation. The earth’s rotation on its
              axis causes day and night. The part

              of the earth that faces the sun and
              receives  light  has day, and on the                    Sun
              other hand, the part of the earth that

              is away from the sun and does not                                    Day and Night
              get light has night.


              Why Do We Have Seasons?

                                                                           There are three main seasons in
                                                                 Orbit     India –  winter, summer  and

                                                                           monsoon. The earth revolves
                                                                           around sun in its own orbit and
                                                                           takes 365 days and 6 hours to


                                         Sun                               complete this revolution. An orbit
                                                                           is a fixed path that one object in
                                                                           space takes around another. The

                                                                           part  of the earth  which faces the
                                                                           sun has warmer and longer days.
                                                                           This part has summer season. On

                                                                           the contrary, the part which is far
                        Earth Revolving Around the Sun                     from the sun has cooler and shorter

                                                                           days. This part has winter season.
              Therefore, changes in seasons are caused by the earth’s revolution around the sun.



              82       Active Science-4]]></page><page Index="76"><![CDATA[The Sun Causes Winds To Blow

                                                     The heat of the sun affects the wind’s movement.
                                                     The air heats up because of the sun’s heat and so,

                                                     air gets lighter. The warmer and lighter air rises to
                                                     flow.In turn, the heavier cool air comes in to take

                                                     its place. This results in the continuous movement
                                                     of air causing winds.


            How Are Clouds Formed?

            The sun’s heat changes the water into water vapour. The amount of water vapour
            present in the atmosphere is called humidity. As the water vapour rises high up
            in the sky, it cools down and condenses into tiny droplets of water. As a result,
            these droplets combine and form clouds. When these clouds get too heavy and can

            no longer hold the water, they fall as rain on the earth. Therefore, the sun plays a
            crucial role in changing the states of water.



             A ir

            Air is very important for all living things to breath. We can feel the air but we
            cannot see it. It is made up of different gases and contains water vapour, dust
            particles and smoke. Simple moving air is called wind. Wind which is gentle is

            called breeze. Strong and fast air is called gale. Very fast and strong wind can
            cause storms.

            The seawater loses heat more slowly than land and it does not lose the same
            amount of heat at the same time. This difference gives rise to sea breeze and

            land breeze. Let us see how it
            happens.                                         Low
                                                           Pressure
            Sea Breeze

            During daytime, the sea does                                           Sea Breeze         High
            not heat up as quickly as land.                                                         Pressure
            The air above land heats up
            because of the heated land.                   Land heats up
            Being lighter, the hot air rises                during day

            up. To fill this space, the cool                                           Sea water is cool during day
            air from the sea blows towards                                                  compared to land
            the land. The wind which blows
            from sea to land during the day
            is called sea breeze.                                              Sea Breeze


                                                                                                                    83
                                                                                             Active Science-4]]></page><page Index="77"><![CDATA[Land Breeze
                                                                High
              At night, land cools down more                  Pressure
              quickly than the sea, cooling

              the air above the land. The air                                          Land Breeze
              above the sea is warmer and

              rises up. The cool air blows from                                                                Low
              land towards the sea to take its                Land cools down                               Pressure
              place. Therefore, the wind that                      at night                    The sea water is

              blows from land towards the sea                                                   warm at night
              at night is called land breeze.

                                                                                    Land Breeze
              Let’s Recapitulate


                  Fill in the blanks.
                  1.  The earth moves on its own axis. It is called ______________.

                  2.  The earth moves around the sun in its own orbit. It is called ______________.
                  3.  The earth takes ______________ to complete one revolution.

                  4.  The wind which blows from sea towards land during the day is called ______________.



               Water

              Water is a necessity for our survival. It is the primary requirement of our life. Most

              of our body weight is made up of water. About 3/4  part of the earth is covered with
                                                                             th
              water. All the living beings need water to live. There are three forms of water – ice,
              water and water vapour. We not only find water in oceans, rivers, sea; it is also

              found under the ground. Let us read in detail.


              Evaporation
              The process in which water changes into water vapour on heating is called

              evaporation. More water gets evaporated when the weather is hot. The amount
              of water vapour present in the atmosphere is called humidity.


              Condensation

              When water vapour changes into water due to cooling, it is
              called condensation. Forms of water like fog, dew, frost,

              hail and snow are all occur due to condensation. When a
              glass of cold water is placed in the open, we see tiny water




              84       Active Science-4]]></page><page Index="78"><![CDATA[droplets on its outside. The water vapour in the atmosphere comes in contact with
            the cool glass and condenses to form water droplets.

            Likewise, fog is a thick layer of clouds made of tiny drops of water. Dew can be

            seen in the early morning during winters in the form of tiny drops of water on
            grass and leaves. Frost is seen when water freezes into tiny white crystals. Hail

            is formed when the freezing raindrops pass through a very cold region. Snow is
            formed when water vapour freezes into white snowflakes.



            Activity 9.1

            Aim                       :  Observing evaporation and condensation.

            Materials Required :  A cotton cloth, a glass of cold juice.


            Procedure                  :  1.  Wash a handkerchief and keep it out under sunlight.

                                        2.  Also fill a glass of cold juice and keep it aside.

                                        3.  Observe both the things after an hour.

            Observation               :   You will find that the cloth has dried up. You will also find tiny

                                          droplets of water on the outer surface of the glass.

            Conclusion                :   The water in the cloth has evaporated due to the heat of the sun.
                                          In case of the glass, the water vapour present in the air condensed

                                          on the outer surface of the glass and so, tiny water droplets were seen.



             Water Cycle

            The water of lakes and rivers

            changes into water vapour
            due to the sun’s heat. This
            water vapour rises up in the                                                              Rain & Snow

            atmosphere and cools  down
            into tiny drops of water. These
            drops combine together and                Evaporation

            make clouds. On becoming
            heavy, the clouds fall on                                Ground Water
            earth as rain or snow. This

            continuous        circulation       of
            water  in  the air and on the                                           Water cycle     Water table

            earth is called water cycle.

                                                                                                                    85
                                                                                             Active Science-4]]></page><page Index="79"><![CDATA[Some of the water that falls on the ground percolates or seeps underground and is
              deposited as the water table under the earth.




               Water Purification

              Water contains substances like dirt, sand and germs which makes water impure.
              Consuming such water can cause many diseases. Therefore, we should purify
              water before drinking.


              Boiling is the easiest method to purify water. It kills germs present in water.
              After boiling, we should keep water in covered containers. Modern day filters are
              also well equipped to have cold water.



               S edimentation and Decantation
                                                                     Percolation
              Sedimentation           and      decantation        are      the

              processes to separate impurities from water. In
              sedimentation, we allow impure water to stand
              undisturbed so that the impurities may settle down

              on the surface of the container. In decantation,
              water in the same container is poured into another
              container without letting in the impurities.                      Sedimentation        Decantation




               F iltration
              In the process of filtration, we use filter paper to separate the insoluble impurities

              from water. In this process, water is passes through the filter paper leaving the
              impurities behind. Water taps usually have filters inside them so as to give pure

              water.


               C hlorination


              Water from rivers and lakes before supplying to our homes is purified by using to
              kill the harmful germs. This process is called chlorination. It makes the water
              safe for drinking.



               S ave Water

              We should not waste water because it is the most valuable natural resource. We
              cannot think of life without water. Water is required for several purposes like

              drinking, bathing, cooking, etc. There are many ways to save water.


              86       Active Science-4]]></page><page Index="80"><![CDATA[1.  Turn off the taps properly.

                 2.  Do not leave the tap open while brushing, washing clothes and washing dishes.

                 3.  Do not wash your cars with pipes, instead use a bucket.

                 4.  Applying rainwater harvesting technique in our homes. It is the collection

                     and storage of rainwater for using later.



            Let’s Recapitulate

                Fill in the blanks.

                1.  About ______________ of the earth is covered with water.
                     a. 1/4 th                          b. 3/4 th                           c. 1/2

                2.  The amount of water vapour present in the atmosphere is called ______________.
                    a. evaporation                      b. fog                              c. humidity

                3.  ______________ is a thick layer of clouds made up of tiny drops of water.
                    a. Dew                              b. Mist                             c. Frost

                4.  ______________ is the easiest method to purify water.
                    a. Boiling                          b. Decantation                      c. Evaporation



                   LET’S
                  REVISE


              •  The condition of atmosphere around us at a specific time is called weather.

              •  The part of the earth which is close to the sun has warmer and longer days.
              •  The earth revolves around the sun on its own axis and takes 365 days and 6 hours to

                 complete one cycle.
              •  Seawater does not heat up as quickly as land during the day. The air gets heated up

                 because of the heat of the land.
              •  Water continuously changes its form from liquid to vapour in nature. This works as a

                 continuous cycle.
              •  Boiling, sedimentation, decantation, filtration and chlorination are the methods to
                 purify the water.




                          Let’s Pronounce Together

                          revolution            rotation                 humidity               filtration
                          chlorination          sedimentation            decantation




                                                                                                                    87
                                                                                             Active Science-4]]></page><page Index="81"><![CDATA[Glossary
                   •  Rotation             :   The movement of the earth around the sun on its own axis.

                   •  Revolution           :   The movement of the earth around the sun in its own orbit.

                   •  Sedimentation  :   To separate the insoluble impurities from water is called
                                             sedimentation.
                   •  Decantation          :   Water is poured into another vessel after sedimentation.

                   •  Filtration           :   To separate the insoluble impurities from water using filter
                                             paper.
                   •  Chlorination         :   To add chlorine into water to kill the harmful germs.





              Practice Time

                  A. Tick the correct option.

                  1.  Changes in weather are caused due to ______________.

                      a. rotation of the sun                               b. rotation of the earth
                      c. revolution of the earth                           d. revolution of the sun

                  2.  The earth takes ______________ to complete one revolution.
                      a. 366 days                                          b. 365 days

                      c. 24 hours                                          d. 365 days and 6 hours

                  3.  The wind which blows from sea to land is called ______________.
                      a. sea breeze                                        b. land breeze

                      c. air breeze                                        d. sun breeze
                  4.  The process of water changing into water vapour by heat is called ______________.

                      a. evaporation                                       b. sedimentation
                      c. decantation                                       d. condensation


                  B. Fill in the blanks.
                  1.  The portion of the earth which faces the sun has _____________ season.

                  2.  The portion of the earth which faces away from the sun has _____________ season.

                  3.  Moving air is called _____________.
                  4.  We feel _____________ breeze during daytime.

                  5.  The process of separating insoluble impurities from water using filter paper is
                      called _____________.
                  6.  The process of adding chlorine into water to kill the harmful germs is called
                      _____________.




              88       Active Science-4]]></page><page Index="82"><![CDATA[7.  At night, land cools down much faster than _____________.
                8.  The amount of water vapour present in the atmosphere is known as _____________.


                C. Label the diagrams.
























                D. Short Answer Questions.
                1.  What is chlorination?

                2.  Write two methods to purify water.
                3.  What do you mean by revolution?

                4.  What is sea breeze?

                E. Long Answer Questions.

                1.  What is land breeze? How does it occur?
                2.  What causes day and night?

                3.  Differentiate between condensation and evaporation.

                4.  What is filtration? Why is purification of water necessary?




            Think Hard

            You must have seen rainwater falling off the roof of your house many times. Can you
            think of at least two ways in which you can use this rainwater?




            Project Work

            Prepare a set up to show sedimentation and decantation.




            Life Skills Activity

            Find out any five water borne diseases, their causes, prevention and cure.


                                                                                                                    89
                                                                                             Active Science-4]]></page><page Index="83"><![CDATA[Research and Development

              Weather is a very unpredictable phenomena. Surf the internet to find out different times

              when water related calamities took place in India in the last five years.




              Field Trip
              Take a road trip around your house and fix up three different spots. Take a strip of paper

              and apply vaseline on one end. Fix the other end at a safe height at these different spots

              that you have identified. Reach out for the strips again after one hour. What do you
              observe?



                   Net Work

                •  To study the water cycle experiment, log on to http://shoalwater.nsw.gov.au/education/

                   watercycle_experiment.htm

                •  Study several ways to save water on http://shoalwater.nsw.gov.au/education/saving_
                   water.htm















































              90       Active Science-4]]></page><page Index="84"><![CDATA[The Solar System

                        10












            Learning Objectives


                   To Understand:
                   •  The solar system                                   •  The satellites
                   •  The stars                                          •  Motion of the earth



                   To Find Out:
                   •  What is atmosphere?                                •  About craters

                   •  How seasons are formed?




            Let’s Begin

            In the given word box, find out and encircle five words related to space.





                     A          H          P          L         A          N          E          T          S


                     K          P          O          V          I         A           I         D          T


                     W          Q          Z          N          R          I         F          U          A


                     E          R          C          S          Z         E          X          P          R

                     P          X          U          U         O          F          V          R          S


                     M          O          O          N          V         X          B          A          Q


                     B          N          R          Y         U          L          M          C          V


                     S          A          T          E          L         L           I         T          E





                                                                                                                     91
                                                                                              Active Science-4]]></page><page Index="85"><![CDATA[S olar System

              Our  solar system consists of the sun, the eight planets and their respective
              moons. All the planets are constantly revolving around the sun in their fixed path

              called orbit. The planets listed in increasing order of their distance from the sun
              are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.




                             The Sun                                                                 Neptune

                                                                          Saturn

                                                                                         Uranus
                                                    Mars



                                        Venus
                                                  Earth          Jupiter


                                  Mercury









              Let us read more about every member of the solar system.


                                                                                   Factual Study
              Sun
                                                                                   The sun has thin outer layer
              Sun is a huge ball of hot gases placed in the
              centre of the solar system. It does not rotate or                    called corona and its central

              revolve but remains fixed at one point. The sun                      part is called a core.
              gives out heat and light to all the planets in the
              solar system. This heat and light has made life

              possible on the earth. The temperature of the
              surface of the sun is about 5500° Celsius.


              Mercury

              It is the smallest planet of the solar system and                           Sun
              is placed closest to the sun. It has no moon and
              is named after the Roman messenger of Gods.

              Mercury is the second hottest planet because of
              its nearners to the sun.                                                                     Mercury




              92       Active Science-4]]></page><page Index="86"><![CDATA[Venus

            It is known as the morning star or evening star. Venus it is
            the second brightest object visible in the sky after the moon. It is

            the hottest planet and is placed between mercury and earth.
                                                                                                        Venus

                                      Earth

                                      It is the only planet which supports life. It is the third planet
                                      from the sun and has one moon that revolves around it. About

                                      70% of its surface is covered with water. So it is also called the
                                      blue planet. The air that surrounds the earth is called its

                                      atmosphere. It protects us from the harmful radiations of the

                    Earth             sun.

            Mars

            It is the second smallest and the fourth planet from the

            sun. The soil and rocks on this planet give it a red colour.
            Therefore, it is also called the red planet. It has two moons

            called Phobos and Deimos.                                                                   Mars


                                      Jupiter

                                      It is the largest and fifth planet from the sun. It has the

                                      maximum number of moons of which more than 65 have
                                      been identified. Jupiter is also the fastest spinning planet
                                      and completes one rotation in just 10 hours. This high speed

                                      creates clouds around it that give it a striped pattern. It is the

                                      third brightest object in the sky after moon and Venus. The
                    Jupiter           jupiter can be seen with the naked eye.


            Saturn

            It is the second largest planet after Jupiter                 Factual Study
            and sixth planet from the sun. It is known                    The ring system which

            as the ringed planet because of the presence                  surrounds Saturn was
            of rings around it. 62 moons revolve around                   first discovered by             Saturn

            Saturn. It is a cold planet and its surface                   Galileo Galilee in the
            temperature is about – 130 degrees Celsius.                   year 1610.




                                                                                                                    93
                                                                                             Active Science-4]]></page><page Index="87"><![CDATA[Uranus

              It is third largest in the solar system and the seventh planet

              from the sun. Uranus is  the  coldest planet  where surface
              temperature may drop to –22  Celsius. It is pale blue in colour
                                                    0
              and was the first planet that was discovered using a telescope.
                                                                                                        Uranus


                                        Neptune

                                        It is the fourth largest and the farthest planet from sun. It has
                                        14 moons revolving around it. Neptune is a very cold planet

                                        and is not visible to the naked eye. It has the fastest blowing
                                        winds and hurricanes in the solar system.
                     Neptune


              Dwarf Planet

              Dwarf planets are those planets which do not fall in the category of planets but

              revolve around the sun. Pluto which was earlier classified as the ninth planet
              is  now known as a dwarf planet. There are many dwarf planets in the solar
              system but only five of them have been discovered and named. These are Ceres,

              Makemake, Eris, Haumea and Pluto.



              Satellites

              A satellite is an object which revolves around the planet in a fixed path called

              its orbit. It is also called the moon of the planet. Every planet, except Mercury
              and Venus, has a moon or moons. There are two types of satellites-natural and
              artificial.




              Natural Satellite
                                                                                    Factual Study
              Moon is the natural satellite of earth. It takes                      The first person to set foot on

              27 days to complete one revolution around the                         the moon was Neil Armstrong.
              earth. Moon does not have an atmosphere and                           He travelled in a spacecraft

              light but it appears bright as it reflects the                        called Apollo 11 and landed on
              light of the sun. Like the planets, moons do not                      the moon on 21  July, 1969.
                                                                                                     st
              have their own light. Its surface is covered with
              large-sized holes called craters. Life is not possible on the moon as it has no air.






              94       Active Science-4]]></page><page Index="88"><![CDATA[Artificial Satellites

            Artificial  satellites are  those objects which are made by man  and sent into
            space to orbit a planet. They are launched using powerful space rockets and keep

            revolving around a planet. The first man-made satellite was Sputnik 1, launched
            by Russia in the year 1957. Since then thousands of satellites have been made by

            different countries. India made its first satellite in the year 1975 and named it
            Aryabhatta.


            Let’s Recapitulate


                Fill in the blanks.
                1.  ______________ is the largest object in the solar system.

                2.  ______________ is also called the blue planet.
                3.  ______________ is the second largest planet after Jupiter.

                4.  The farthest planet from the sun is ______________.



              S tars

            Stars are small twinkling objects in the sky which

            can be seen only at night. They are huge balls of hot
            gases which produce their own heat and light. They
            are of different colours and sizes. There are millions

            of stars in our galaxy, Milky Way, and some of them
            are larger than the sun. We cannot see the stars
            during daytime because the sun is much brighter

            as compared to them. They are far from the earth
            so they look like tiny spots. The sun is the nearest                               Milky way

            star to the earth and therefore appears so big and                                  North
            bright.                                                                              Pole
                                                                                  Equator                 Axis of
                                                                                                   23.5 0  Rotation
             Motion Of The Earth
                                                                                                            Northern
            The earth not only revolves around the sun on its orbit                                       Hemisphere
            but also rotates on its own axis. The axis is an imaginary

            the line passing through the North Pole, South Pole and                                         Southern
            centre of the earth. The earth is tilted at an angle of                                        Hemisphere
            23.5 degrees on its axis and rotates from west to east.

            Another imaginary line that  divides the earth into                    South
                                                                                    Pole

                                                                                                                    95
                                                                                             Active Science-4]]></page><page Index="89"><![CDATA[two equal parts, Northern hemisphere and Southern hemisphere, is called the
              equator. The equator is drawn at an equal distance from the North and South Poles.




              Activity 10.1

              Study the map of the world and make a list of the countries and oceans through which
              the equator passes. Explain the climatic characteristics of those places.



             Other Objects in the Solar System

             There are some other objects that orbit around the sun. These are  asteroids,
             meteoroids and comets.
















                        Asteroids                          Meteoroid                         Shooting Stars

             Asteroids are rocky objects which range in size from about the size of pebbles to

             around 1000 km across. They are thought to be leftover material from the formation
             of solar system.
             Meteoroids are small bodies moving in the solar system. When they enter the

             earth’s atmosphere, they burn up and look like fireworks in the sky. Then they are
             called meteors or shooting stars.

             Comets are small heavenly bodies that

             orbit the sun. They are mainly made of
             dust and ice.




                 Factual Study

                 Halley’s comet is the most common well

                 known comet in the solar system. As
                 Halley comes closer the sun, it releases
                 jets of gases which appear like a bright

                 tail. It was last seen in 1986.

                                                                                            Comet


              96       Active Science-4]]></page><page Index="90"><![CDATA[Factual Study

            •  The sun is so huge that about one million earths can fit into it.
            •  The highest mountain in the solar system is on Mars. It is called Olympus Mons and is three

                times higher than Mount Everest.


            Activity 10.2


            Arrange the planets of solar system in the right order in your notebook.






















            Let’s Recapitulate

                State whether the following statements are true or false.
                1.  The earth not only revolves along its orbit but also rotates on its own axis. ______

                2.  Meteors are small twinkling objects in the sky which
                    can be seen only at night.                                                                 ______

                3.  The equator is drawn at a different distance from the
                    North and South Poles.                                                                     ______
                4.  The earth takes 365 days or one year to complete one revolution around
                     the sun in its orbit.                                                                     ______




                   LET’S
                  REVISE


              •  In our solar system, the eight planets and their moon revolve around the sun.
              •  The sun is a huge ball of hot gases which provides energy to all the living things on

                 earth. It is situated at the centre of the solar system.
                                                                                     Let’s Pronounce Together
              •  Earth is the only planet which supports life. It is the

                 third closest planet to the sun and one moon moves                  planets       satellites
                 around it. About 70% of earth is covered with water.                equator       dwarf
                                                                                     planet



                                                                                                                    97
                                                                                             Active Science-4]]></page><page Index="91"><![CDATA[•  Dwarf planets are those planets which do not fall in the category of planets but
                   revolve around the sun.

                •  The natural satellite of the earth is the moon.
                •  Stars are small twinkling objects in the sky which can be seen during night.




              Glossary
                   • Solar system                :  It consists of the sun, the eight planets and their respective
                                                   moons.
                   •   Stars                     :  Small twinkling objects in the sky which can be seen only at
                                                   night.
                   •   Equator                   :  An imaginary line passing through the centre of earth.
                   •   Dwarf planet              :  An object which revolves around the sun but is not large
                                                   enough to be called a planet.
                   •   Craters                   :  The large pits on the surface of a planet formed when a
                                                   meteor or an asteroid collides with it.
                   •   Satellite                 :  An object which revolves around the planet on a fixed
                                                   path.
                   •   Artificial Satellites  :  Man-made satellites.




              Practice Time


                  A. Tick the correct option.
                  1.  Uranus is a _____________.

                      a. satellite                                         b. planet

                      c. star                                              d. dwarf planet
                  2.  _____________ is also called blue planet.

                      a. Earth                                             b. Sun
                      c. Venus                                             d. Saturn

                  3.  _____________ is the second largest planet after Jupiter.
                      a. Saturn                                            b. earth

                      c. Sun                                               d. Neptune

                  4.  _____________ is the coldest planet.
                      a. Uranus                                            b. Neptune

                      c. Earth                                             d. Star

                  B. Fill in the blanks.

                  1.  The planets revolve around the sun in fixed _____________.
                  2.  The temperature of the surface of the sun is about _____________ degree Celsius.


              98       Active Science-4]]></page><page Index="92"><![CDATA[3.  _____________ is the second hottest planet.
                4.  _____________ is the second brightest object in the sky.

                5.  _____________ and _____________ are the two moons of Mars.
                6.  _____________ is the fastest spinning planet.

                7.  The surface temperature of Saturn is _____________ degree Celsius.

                C. Give one word for each of the following.

                1.  I am the hottest planet.                                                           ____________

                2.  I am also known as the ringed planet.                                              ____________
                3.  It is the smallest and closet to the sun.                                          ____________

                4.  I am known as the red planet.                                                      ____________
                5.  The seventh planet from the sun.                                                   ____________

                6.  The biggest object in the solar system.                                            ____________
                D. Short Answer Questions.

                1.  How long does the earth take to complete one revolution around the sun?

                2.  What is a satellite?
                3.  What are dwarf planets?

                4.  How many planets are there in our solar system?
                5.  Why is earth called the “blue planet”?


                E. Long Answer Questions.
                1.  Describe the planets Venus and Mars.

                2.  Why can we see stars only at night?
                3.  What is the equator?

                4.  How are the seasons formed?

                5.  What causes day and night?

                F. Label the picture given below.
                                                                          ______________


                                       ______________                         ______________















                                        ______________

                                                                                                                    99
                                                                                             Active Science-4]]></page><page Index="93"><![CDATA[G. Draw and explain.
                      The solar system.




              Think Hard

              Suppose the earth stopped revolving around the sun for 24 hours. What would happen?




              Project Work

              Make a solar system with the help of fruits. Choose different fruits depending on their

              size to depict different planets.




              Life Skills Activity
              The planet earth is unique as it is the only planet on which life is possible. Therefore,

              it is our duty to look after its well-being and help everyone have a wonderful life here.

              Think about how you can contribute towards improving life on earth.




              Research and Development
              Find out why the stars don’t fall on the earth.




              Field Trip

              Find out about a science museum around your area. Plan a visit to the same.




                   Net Work

               •  To know about the MOM, log on to http://www.ndtv.com/cheat-sheet/mangalyaan-makes-
                   history-top-10-facts-670808


               •  To play a game with the solar system, visit http://www.softschools.com/science/space/
                   solar_system_kids_games/

















              100      Active Science-4]]></page><page Index="94"><![CDATA[Keeping the


                        11                      Earth Green












            Learning Objectives


                   To Understand:
                   •  Importance of trees                                •  Saving trees


                   To Find Out:
                   •  What is deforestation?                             •  What is afforestation?




            Let’s Begin


            Write few lines on the given topic.


                                                To keep the earth clean
            I can

            ___________________________________________________________________________

            ___________________________________________________________________________

            ___________________________________________________________________________

            My family can

            ___________________________________________________________________________

            ___________________________________________________________________________

            ___________________________________________________________________________

            My school can


            ___________________________________________________________________________
            ___________________________________________________________________________


            ___________________________________________________________________________



                                                                                                                    101
                                                                                              Active Science-4]]></page><page Index="95"><![CDATA[Plants and trees make our surroundings clean and fresh. They make our earth
              pure and beautiful. Plants have great importance in our life. Without plants and

              trees we cannot expect life on the earth. They give us food, fuel, shelter, clothes,
              etc. They are helpful in many ways. Trees help in bringing rain. Rains, in turn,
              fulfil our requirement of water.


              We depend so much on trees that we cut them frequently to meet our requirements.
              This excessive cutting of trees  has led to the shortage of food, water and shelter
              for the animals in the forest.




                I mportance Of Trees

              Our life depends on food, clothing, shelter and water, and trees provide us all of
              them. They help us in many ways:

                  1.  We get food from them in the form of

                       fruits, vegetables, spices and seeds,
                       etc.                                                                          Factual Study
                                                                                                  •  Trees have been
                  2.  We get air (oxygen) to breath.                                                 in existence on
                                                                               Timber
                  3.  They prevent soil erosion.                                                     the earth for 370
                                                                                                     million years.
                  4.  They are helpful in bringing rain.
                                                                                                  •  No trees die of
                  5.  They provide us raw materials                                                  old age. They
                       like wood to make paper, timber                                               are generally

                       to make furniture and firewood for                        Table               killed by insects,
                       fuel, etc.                                                                    diseases or cut by

                                                                                                     people.
                  6.  They provide us with shelter.

                  7.  Trees also provide us medicines.
                                                                               Firewood

                                                                       We are cutting more trees day by
                                                                       day to meet our needs. Cutting

                                                                       down trees in huge numbers is
                                                                       called  deforestation. Deforestation

                                                                       has many harmful effects on the
                  Deforestation                 Cutting Trees          environment like causing impure air,
              less rainfall, soil erosion, etc., so we should plant more trees.







              102      Active Science-4]]></page><page Index="96"><![CDATA[S aving Trees                               SAVE US

            Trees are very important for
            us, so we should not destroy

            them. They take many years to
            grow. They protect us from the
            exposure of sun and wind.


            Some ways to save trees and
            keep the earth green are:

                 1.  Plant trees in large numbers. Planting of a large number of trees on a barren

                     land is called afforestation.

                 2.  We should use the products which we get from trees wisely.

                 3.  Use electricity wisely.

                 4.  Choose paperless options for bills and ask for ebills.


                 5.  Encourage refuse, reuse and recycle.

                 6.  Share your love for trees and forests with other people.

            We should educate people to organise programmes like Van Mahotsava. We should

            tell people about the good and bad effects of cutting trees.

            The United Nations established the World Environment Day in 1972. Every
            year, it is celebrated on June 5 in many countries. The Earth anthem was also

            inaugurated in 2013. On this day, people are encouraged and taught to save trees
            to protect living beings from the adverse effects on nature.



            Let’s Recapitulate

                Complete the blanks.

                1.  Plants help us in many ways like ______________________.

                2.  Growing plants in huge quantity is called ______________.
                3.  To cut the trees in huge quantity is called ______________.

                4.  Trees provide us raw material like ______________________.




              Let’s Pronounce Together

              deforestation          afforestation            destruction          surroundings          adverse



                                                                                                                   103
                                                                                             Active Science-4]]></page><page Index="97"><![CDATA[LET’S
                    REVISE

                •  Plants and trees make our surroundings clean and fresh.

                •  Trees provide us raw material like wood to make paper, timber to make furniture
                   and firewood for fuel, etc.

                •  They provide medicines.
                •  We are cutting excessive trees to meet our needs.







              Glossary
                   •  Deforestation  :  To cut trees in huge numbers.

                   •  Afforestation  :  Plant more trees on barren land.





              Practice Time

                  A. Tick the correct option.

                  1.  The destruction of forests leads to shortage of _____________.
                      a. plants                                            b. food

                      c. animals                                           d. birds
                  2.  Which of the following is made of wood?

                      a. Table                                             b. Freezer

                      c. Television                                        d. Oven
                  3.  Trees give us _____________.

                      a. oxygen                                            b. nitrogen
                      c. carbon dioxide                                    d. none of these

                  4.  Cutting many trees is called _____________.
                      a. deforestation                                     b. afforestation

                      c. plantation                                        d. none of these

                  B. Fill in the blanks.

                  1.  Trees provide us clean air to _____________.

                  2.  We get _____________ for industries from trees.
                  3.  We should plant more trees to reduce the harmful effects of _____________.

                  4.  Organise events like _____________ to plant trees.




              104      Active Science-4]]></page><page Index="98"><![CDATA[C. Short Answer Questios.
                1.  What is deforestation?

                2.  What is afforestation?
                3.  What is Van Mahotsava?

                4.  What is the role of trees in  maintaining the quality of air?

                D. Long Answer Questions.

                1.  How can we save trees?
                2.  Write five ways in which trees are important for us.

                3.  How can we spread awareness among people about afforestation?
                4.  What are the effects of deforestation?




            Think Hard

            If there were no trees, what would happen? Imagine and write in your own words.




            Life Skills Activity

            Prepare a speech on ‘Growing More Trees’ to be delivered in your class. Think about how

            you can contribute towards improving life on the earth.




            Research and Development

            1.  Two medicinal plants and the medicines we get from them.

            2.  Two industrial plants and the raw materials that they provide.




            Project Work

            Make a poster and write a slogan to                 Net Work
            encourage people to save trees.                  •  To play a game on recycling, log on to http://www.
                                                                primarygames.com/holidays/earth_day/games/
                                                                michaelmichaelgorecycle/
            Field Trip                                       •  To find facts on the environment, visit http://blog.

            Visit your neighbourhood and do a                   goinggreentoday.com/10-green-facts-that-will-

            survey  on  how  many  people  plant                make-your-head-spin/comment-page-1/
            trees at least in a year.                        •  To see the tips to keep the environment clean,

                                                                log on to http://ecoadmirer.com/keep-earth-clean-
                                                                save-green/


                                                                                                                   105
                                                                                             Active Science-4]]></page><page Index="99"><![CDATA[SOIL

                        12












              Learning Objectives


                     To Understand:
                     •  Soil formation                              •  Soil composition
                     •  Types of soil                               •  Soil profile

                     •  Soil erosion                                •  Soil conservation


                     To Find Out:
                     •  About weathering                            •  What is top soil, subsoil and bedrock?
                     •  The colour and size of the soil




              Let’s Begin

              Soil is a very important natural resource. Plants grow in soil. Human and animals

              depend on plants for their food. Besides producing food, soil also acts as a home to
              a variety of insects and animals.




               F ormation Of Soil

              The development of soil is a slow process as it takes hundreds of years to form just

              1cm of soil. Natural agents such as the heat of the sun, strong winds and flowing

              water break the big rocks into small pieces leading to the formation of soil. This

              process is called weathering.

              The roots of plants  grow and penetrate the rocks to break them into small particles.

              Burrowing animals also break rocks into smaller pieces. These small pieces further

              disintegrate into small sized, fine textured particles called sand. In this way, a
              thin layer of soil is created. The remains of dead plants and animals are broken



             106      Active Science-4]]></page><page Index="100"><![CDATA[down by the  action of micro-organisms

            present in soil. This produces a fertile layer
            of soil called humus. Soil occurs in different

            colours like dark-brown, black and red,

            depending on the climate and place.

            Hence, soil is the topmost layer of the earth’s

            surface. It contains fine particles  like sand,

            humus, minerals, air, organic  matter and
            water.




              S oil Composition

            Soil is a mixture of many different things. The five basic components of soil are as
            listed below:

                 1.  Rock material                         2.  Organic material


                 3.  Air                                   4.  Water                           5.  Soil creatures

            Rock Material

            Sand, silt and clay are small particles of rock. These are

            formed by weathering of rock and constitute the inorganic
            or the non-living component of the soil. Some of these are
            large enough to be visible while others are very fine and
            microscopic. The stones and pebbles are the large visible

            components while sand and silt, although small; also form
            a part of the visible matter. Very fine particles, closely
            packed together form clay. The inorganic component of the                          Rock Material

            soil constitutes about half of its total mass.


            Organic Material
                                            The dark-brown material formed by the decay of plant

                                            and animal residue is called humus. It forms the organic
                                            component of the soil. Humus is a rich source of minerals

                                            and makes the soil fertile. It helps in the growth of plants
                                            and helps the soil to hold more water. It is rich in nutrients
                                            essential for the growth of plants.
                     Humus



                                                                                                                   107
                                                                                             Active Science-4]]></page><page Index="101"><![CDATA[Factual Study
               A ir
                                                                              The air in the soil has less oxygen
              All the organisms that live in the soil
              require air to breathe. Therefore, soil also                    and more carbon dioxide. This
              contains oxygen and carbon dioxide which                        carbon dioxide escapes from the soil

              remain trapped in small holes or cavities                       cavities and helps to replenish the
              within the soil. Another gas found in the soil                  atmospheric levels of carbon dioxide.
              is nitrogen, which is taken up by the plants for their growth. The air in the soil
              is more humid as compared to the atmospheric air and has a higher proportion of

              carbon dioxide in comparison to oxygen. This is because the organisms living in
              the soil use most of the oxygen to breathe and exhale carbon dioxide.


               Water

              Water is a very important component of the soil. It is used by the plants and soil
              organisms to survive. Water also dissolves many substances and nutrients in it.


               L iving Things

              There are many living organisms in the soil like
              earthworms, microorganisms, tiny insects which help
              in the development of humus. Earthworms help in
              circulating air through the soil by making burrows.

              The excreta of the earthworm is used as food by other
              microbes.


                    Factual Study                 45% Rock Material                         Living Things in Soil

                 Soil acts as a filter for        25% Air

                 underground water as it          25% Water
                 filters out pollutants.
                                                  5% Organic Material and living things


              Activity 12.1

              To identify various components of soil


              Visit a nearby garden or a park. Look closely at the soil and make the following
              observations:

              1. What is the colour of the soil?

              2. How does it smell like?
              3. Hold some soil in your hand and note what it feels like.

              4. Is the soil moist or dry?


              108      Active Science-4]]></page><page Index="102"><![CDATA[T ypes of Soil

            Soil can be divided into three main types

            based on the size, feel (texture) and colour
            of constituent particles. These are sandy,

            clayey and loamy.


            Sandy soil is largely made up of sand which                        Sand
            is smaller in size as compared to gravel.

            The sand particles have gaps between them
            which are filled with air.


            Sandy soils are light, dry and well-aerated.

            These soils are very good for growing
            coconut trees, carrots, beetroot and many                                                     Clay

            herbs.


            Clayey soil is made up of very fine particles
            which are very small in size. There is very

            little space between these particles and
            therefore this soil holds more water. It is

            quite sticky and heavy. This kind of soil is

            very good for the growth of cereal crops.
                                                                               Loam
            Loamy soil is best for growing plants as it

            is a mixture of sand, clay and humus. It has

            a sufficient amount of humus, nutrients
            and holds adequate amount of water. It is very fertile.


            Let’s Recapitulate


                Complete the blanks.

                1.  The natural process of breakdown of rocks is known as ______________.

                2.  ______________ soil is very good for construction work.
                3.  Cereals grow very well in ______________ soil.

                4.  ______________type of soil cannot hold water well.

                5.  Loamy soil has sufficient amount of______________.



                                                                                                                   109
                                                                                             Active Science-4]]></page><page Index="103"><![CDATA[S oil Profile
              Soil profile refers to the different layers of soil. There are three main layers in soil.

                  1.  Topsoil                            2.  Subsoil                         3.  Bedrock

                  1.   Topsoil : It is the uppermost layer which lies between 2-8 inches from the
                       surface. It is rich in humus, air, water and microorganisms which are very
                       good for the growth of plants. It has fine particles like sand and clay.


                  2.   Subsoil : It lies under the topsoil and contains
                       sand, silt and clay. However, this layer has less
                       organic matter or humus which makes it less
                       fertile in comparison to the topsoil. It also has              Topsoil
                       broken pieces of rocks making it very compact.
                       It does not contain much air but holds water. It                    Subsoil
                       is light in colour.
                                                                                          Bedrock
                  3.   Bedrock  : The lowest layer  at  the bottom
                       of the soil profile is called the bedrock. It has
                       large hard pieces of rocks and can extend to                    Parent rock
                       hundreds of metres under the earth’s surface. It
                       has unweathered rocks. It cannot contain much
                       water.
                                                                                                       Soil Profile
              Soil profile varies from place to place and is greatly
              affected by the climate of an area.




               S oil Erosion
              The process of loss of top fertile layer of soil by
              the action of wind, running water, animals and
              human activities is called soil erosion. It spoils
              the soil quality capacity to grone plants and
              hold water. Various other factors such as heavy

              rainfall, overgrazing by animals, deforestation,
              landslides, flooding and construction by human

              beings can lead to soil erosion.                                                 Soil Erosion




               S oil Conservation
              The humus and microorganisms contained in the topsoil need to be replenished to

              maintain soil quality. Therefore, we should take steps to conserve soil. The process
              of prevention of soil erosion is called soil conservation.




              110      Active Science-4]]></page><page Index="104"><![CDATA[Ways to Conserve Soil
                                                               1.  To prevent the erosion of soil, we should

                                                                   plant more number of trees. The roots of
                                                                   the trees bind the soil thus, do not allow

                                                                   its erosion.

                                                               2.  Prevent overgrazing by cattle. The
                                                                   cattle should be sent to different areas

                                                                   to graze so that the plants and grasses
                Trees Prevent Soil Erosion                         get time to grow back in the areas that
                                                                   have been grazed already.


                                                                   The practice of growing different crops
                                                                   in successive seasons is called  crop
                                                                   rotation. This helps in maintaining soil

                                                                   quality as different crops have different
                                                                   nutrient requirement.

                                                               3.  Building embankments along the river
                              Overgrazing by Cattle                banks to prevent the overflowing water

                                                                   during floods is an effective method of

                                                                   soil conservation. The flood water tends
                                                                   to carry away the topsoil leading to soil
                                                                   erosion.


                                                               4.  Hilly areas are prone to losing the
                                                                   fertile topsoil when rain water flows down
                                                                   the slopes. Building terraces or contours for

                                                                   farming helps to reduce the speed of flowing
                           Crop Rotation                           water and thus prevents loss of fertile soil.


              Let’s Pronounce Together


              weathering                humus                  subsoil                topsoil             bedrock


                   LET’S
                 REVISE


              •  Soil is a very important natural resource.
              •  Formation of soil is a slow process as it takes hundreds of years to form just 1cm

                 thick layer of soil.


                                                                                                                   111
                                                                                             Active Science-4]]></page><page Index="105"><![CDATA[•  The roots of plants break rocks into smaller pieces. These rock pieces are further
                   broken down into smaller particles and are called sand.

                •  Soil is the topmost layer of the earth’s surface. It is made of sand, silt and clay
                   besides organic humus.

                •  Sand, silt and clay are small particles of rock which are formed by weathering.
                •  There are many living things in the soil like earthworms and micro-organisms, which

                   help in the development of humus.
                •  Soil is classified into three types based on its size, feel and colour of particles. These

                   are sandy soil, clayey soil and loamy soil.
                •  The removal of the topsoil by various natural forces and human activities is called

                   soil erosion.
                •  Crop rotation is the practice of cultivating different types of crops on the same

                   farmland in successive seasons. This process makes the soil fertile.



              Glossary

                   •  Topsoil                  :   The uppermost layer of the soil.

                   •  Subsoil                  :   The middle layer of the soil.
                   •  Bedrock                  :   The bottom layer of the soil.
                   •  Crop rotation            :   Growing different types of crops on the same farmland.

                   •  Soil conservation  :   Prevention of erosion of soil.

                   •  Soil erosion             :   The removal of topsoil by the action of either wind or water.




              Practice Time


                  A. Tick the correct option.
                  1.  The process of natural breakdown of rocks is called _____________.

                      a. weathering                                        b. soil erosion

                      c. crop rotation                                     d. soil conservation
                  2.  The uppermost layer of soil is called _____________.

                      a. topsoil                                           b. bedrock
                      c. subsoil                                           d. soil profile

                  3.  This layer contains large pieces of rocks and is very hard. It is called _____________.
                      a. topsoil                                           b. subsoil

                      c. bedrock                                           d. humus




              112      Active Science-4]]></page><page Index="106"><![CDATA[4.  The process which reduces the soil quality is _____________.
                     a. soil erosion                                     b. soil profile

                     c. soil conservation                                d. terrace farming

                B. Fill in the blanks.

                1.  The bottom layer of the soil is called _____________.
                2.  The process of growing different crops on the same farmland is called _____________.

                3.  The organic matter present in the topsoil is called _____________.

                4.  Prevention of soil erosion is called _____________.

                C. State whether the following statements are true or false:

                1.  Topsoil is rich in humus, air and water.                                                   ______
                2.  Subsoil is the lowest layer of the soil.                                                   ______

                3.  Soil erosion reduces the soil quality.                                                     ______

                4.  Planting of trees prevents erosion of soil.                                                ______

                D. Short Answer Questions.
                1.  What is weathering?

                2.  What is soil erosion?
                3.  What is crop rotation?

                4.  What are the main types of soil?

                E. Long Answer Questions.

                1.  What is soil conservation? List the methods of conservation.
                2.  Describe the soil profile with a suitable diagram.

                3.  Write about the process of formation of soil.
                4.  Compare four different types of soil.




            Think Hard

            Soil is often called the skin of the earth. Why?




            Project Work

            Divide the class into groups. Each group creates a model of the soil profile. Topics such as

            soil formation, soil conservation and soil erosion, etc., can be divided amongst the groups
            on which they will create a presentation.






                                                                                                                   113
                                                                                             Active Science-4]]></page><page Index="107"><![CDATA[Life Skills Activity

              Do you think we can cause soil erosion? Think of the various activities that we perform
              which lead to the removal of the topmost fertile layer of soil. How can we prevent it?




              Research and Development

              Pick any one soil organism. Prepare a slide show to explain:

              1.  Its adaptations

              2.  Its feeding habits

              3.  Its special characteristics




              Field Trip

              Go to your garden and segregate the different things or components that you find in the
              soil and put them in separate transparent plastic bags. Label them.



                   Net Work


                •  To learn about earthworms and how they are helpful in maintaining soil fertility, log on
                   to http://kids.nationalgeographic.com/animals/earthworm/










































              114      Active Science-4]]></page><page Index="108"><![CDATA[Solids, Liquids


                        13                        and Gases












            Learning Objectives


                   To Understand:
                   •  States of matter                                   •  Changing states of matter
                   •  Dissolving solids in water



                   To Find Out:
                   •  What is melting and freezing?                      •  How do solids dissolve in water?

                   •  How does water dissolve in everything?




            Let’s Begin

            Match the following:





                                                                                                     Solid
































                                                                                                                    115
                                                                                              Active Science-4]]></page><page Index="109"><![CDATA[All things around us are made up of matter. Matter has mass and it occupies

              space. Even the air we take in and the water which we drink, are matter. Matter

              is made up of tiny particles. Our body is also made up of matter.




               S tates Of Matter

              There are three different states of matter – solid, liquid and gas.

              Activity 13.1


              Write the name of any four solids, liquids and gases in the given space.

              Solids      :   ____________        ____________          ____________         ____________

              Liquids     :   ____________        ____________          ____________         ____________

              Gases       :   ____________        ____________          ____________         ____________




              Solids
              The particles in solids do not have free space in between them. They are closely-
              packed, so they cannot move around. This is the reason solids have a fixed shape,
              size and volume. But we can change the shape of some solids with the help of force.
              Like if we press a quilt, sponge in the quilt will change the shape upon compressing.

              Therefore, solids cannot flow but can change shape of application of force.















                    Quilt                                            Ice                          Arrangement of

              Liquids                                                                            particles in Solids
              Liquids have a fixed volume but they
              do not have a fixed shape. Particles

              in liquids are not close to each other,
              so they can move around a little.
              Therefore, liquids can flow and take

              the shape of the container they are
              poured into.                                                                        Arrangement of
                                                                  Glass of Water                particles in Liquids


              116      Active Science-4]]></page><page Index="110"><![CDATA[Gases

            The particles of gases can easily move in any direction. The particles in gases are
            loosely packed. They neither have fixed shape nor fixed volume. They can flow and

            can also be easily compressed. It occupies all the available space in a container.




















                                                                                                 Arrangement of
              Air Inside a Balloon                          Steam                               particles in Gases

            Now we will see the difference between the properties of solids, liquids and gases.




                          Solids                            Liquids                              Gases



                 They have fixed shape           They have fixed volume but           They have neither fixed
                       and volume.                      no fixed shape.               shape nor fixed volume.



                   The particles have              The particles have more              Space is more than in
                     very less space.               space to move around.                 liquids and solids.


                                                  They can flow from higher                They can flow in
                   They cannot flow.
                                                         to lower level.                    any direction.





            Let’s Recapitulate

                Fill in the blanks.

                1.  _____________ can flow in any direction.

                2.  _____________ have space more than solids.
                3.  Gases have no fixed _____________.

                4.  The things which have mass and occupy space are called _____________.






                                                                                                                   117
                                                                                             Active Science-4]]></page><page Index="111"><![CDATA[C hanging States Of Matter

              Activity 13.2


              Aim                       :  To observe the change in the state of matter from liquid to solid
                                            and solid to gas.

              Materials Required :  A sauce pan, some ice cubes, a burner


              Procedure                  :  1.  Take some ice cubes in a pan.

                                         2.  Start heating.

                                          3.  Observe the changes taking place.


               Observation              :   1.  You will observe that ice has melted
                                                and has changed into water.

                                          2.  You will also observe that liquid

                                                has turned into vapour.

               Conclusion               :  2.  It is clear that matter can change
                                                from one state to another.


              Change in States of Matter

              The particles of matter move freely and leave their fixed position when they get
              heated. Upon heating, the particles change their state – solids melt and turn into
              liquid. This process is called melting. This liquid can be cooled and changed into

              solid. This is called freezing.

              Upon heating a liquid, till a specific point of time, the particles move so far from

              each other that they change into gaseous state. This process is called evaporation.
              When gas changes its state into liquid on contact with a cold surface, it is called
              condensation.




              Let’s Recapitulate

                  State whether the following statements are true or false:
                  1.  The process by which solids change their state into liquid
                      is called evaporation.                                                                    ______

                  2.  Solids cannot flow.                                                                       ______

                  3.  Gas particles occupy all the available space in the container.                            ______
                  4.  Liquids have fixed volume but no fixed shape.                                             ______



              118      Active Science-4]]></page><page Index="112"><![CDATA[D issolving Solids in Water



            Activity 13.3

            Aim                       :  To find out how solids dissolve in liquids.


            Materials Required :  A glass of water, a spoonful of sugar

            Procedure                  :  1.  Take a glass of water.

                                        2.  Mix a spoonful of sugar and stir it.


                                        3.  When you stir for some time, what
                                              will you see?

            Observation               :   We will observe that sugar has started

                                          disappearing.

             Conclusion               :   It happened because sugar has dissolved in the water.

            The solid that dissolve in a liquid is called solute. Water is called a universal solvent

            as everything dissolves in it. There are some solids that dissolve in liquids. The liquid
            in which a solid dissolves is called solvent. After dissolving the solute in the solvent, a
            liquid is obtained. This liquid is called a solution.







                                            +                                        =








                      Solute                                  Solvent                                 Solution


                    Factual Study

                 Liquids like water, oil, soda fit inside the container they kept in. If you look at them
                 under a microscope, you’ll see that they have particles stick close together.






             Let’s Pronounce Together

             solids                   liquids                gases                   solvent             solute

             solution                 freezing               evaporation             condensation


                                                                                                                   119
                                                                                             Active Science-4]]></page><page Index="113"><![CDATA[LET’S
                    REVISE


                •  There are different things around us like air, water, trees, etc. All these things have
                   mass and occupy space, which is called matter.

                •  The particles of solids do not have space, so they cannot move around.
                •  Liquids have a fixed volume but do not have fixed shape. Particles of liquids are not

                   close to each other, so, they cannot move around.
                •  The particles of gases can easily move in any direction. They do not have fixed shape
                   and fixed volume.

                •  We can change the state of matter from liquid to solid and solid to gas.





              Glossary
                   •  Melting             :   Process in which, on heating, a solid changes into liquid.

                   •  Freezing            :  Process in which a liquid changes into a solid.
                   •  Evaporation         :  Process in which, on heating, liquid changes into gas.

                   •  Condensation  :   When gas changes its state into liquid with contact of cold
                                            surface.

                   •  Solute              :   The solid that is dissolved in the liquid.
                   •  Solvent             :   The liquid in which the solute is dissolved.
                   •  Solution            :  Liquid obtained after dissolving a solute into a solvent.





              Practice Time


                  A. Tick the correct option.
                  1.  Liquids do not have fixed _____________.

                      a. shape                                             b. volume
                      c. space                                             d. value

                  2.  Gas particles can move in _____________.

                      a. any direction                                     b. one direction
                      c. both directions                                   d. none of these

                  3.  Gases do not have fixed _____________.
                      a. volume                                            b. space

                      c. value                                             d. none of these





              120      Active Science-4]]></page><page Index="114"><![CDATA[4.  The process by which solid changes into liquid is called _____________.
                     a.  melting                                         b. freezing

                     c.  evaporation                                     d. condensation

                B. Fill in the blanks.

                1.  The process by which a liquid changes into a solid on cooling is called _____________.
                2.  The process by which a liquid changes into gaseous form on heating is called
                    _____________.

                3.  The process by which gas changes into a liquid on cooling is called _____________.

                4.  The solid which dissolves in the liquid is called _____________.
                5.  _____________ have no fixed shape but have fixed volume.

                6.  Matter exists in _____________ states.
                7.  The liquid obtained after dissolving a solute in a solvent is called _____________.

                8.  The particles cannot move _____________ in solids.

                C. State whether the following statements are true or false:

                1.  Solids cannot flow.                                                                        ______
                2.  Liquids do not have fixed volume.                                                          ______

                3.  Gases can flow in all directions.                                                          ______

                4.  The particles are not packed closely to each other in solids.                              ______

                D. Short Answer Questions:

                1.  What is matter?
                2.  What is a solid?

                3.  How does a solute dissolve in a solvent?

                4.  What is condensation?
                5.  What is freezing?

                6.  Write any three properties of gas.

                E. Fill in the three boxes to show the arrangement of molecules in:

















                              Solid                            Liquid                            Gas


                                                                                                                   121
                                                                                             Active Science-4]]></page><page Index="115"><![CDATA[F. Long Answer Questions:
                  1.  Write the properties of solids and liquids.

                  2.  How does matter change its state?
                  3.  What are the similarities between gases and liquids?

                  4.  How do solids dissolve in water? Explain with an activity.




              Think Hard

              If we put gas in a liquid, will the liquid dissolve it or not?




              Project Work

              Cut and paste atleast three solids, liquids and gases in your scrapbook.







              Life Skills Activity

              To what extent do chocolates, butter, aluminium and cold wax melt? Which objects need
              high temperature to change their state?




              Research and Development

              If the atmospheric temperature rises, what will happen? Perform the activity with a
              balloon and find the answer.




              Field Trip

              Visit a dairy and a grocery shop. Try to look up at the space taken by solid grocery items

              and the milk contained in packets or drums.



                   Net Work

                •  To study the experiment on melting of a chocolate, log on to http://www.sciencekids.co.nz/
                   experiments/chocolate.html


                •  To find some more facts on solid, liquid and gas, visit http://www.squizzes.com/solids-
                   liquids-gases/







              122      Active Science-4]]></page><page Index="116"><![CDATA[Force, Work


                        14                       and Energy












            Learning Objectives


                   To Understand:
                   •  Types of forces                                    •  Work
                   •  Simple machines                                    •  Energy and its sources



                   To Find Out:
                   •  How force makes the object move?

                   •  How do machines make our life easy?
                   •  Natural sources of energy.




            Let’s Begin

            In the given below activities, tell whether work is taking place or not.





                                       Direction of Force            Direction of Motion                   Work
                                                                                                          (  or  )
                                                                                                           
                                                                                                                 


























                                                                                                                    123
                                                                                              Active Science-4]]></page><page Index="117"><![CDATA[T ypes Of Forces

              Force means a pull or a push. If someone makes an effort to move an object it is
              called force. There are forces acting all around us all the time. Force can be of

              three types.

                  1.  Gravitational Force                2.  Frictional Force                3.  Muscular Force

                  1.   Gravitational Force : When we                      Factual Study
                       throw something upwards, it will

                       always fall back on the earth. It              •  Gravity makes stars burn by squeezing
                       happens because the earth applies                  their matter together.
                       force called gravitational force               •  Black holes have the strongest
                       on the object. It always pulls the                 gravitational pull in the entire universe.
                       object towards the centre of the
                       earth. If there were no gravity, we would be floating in the air.

                  2.   Frictional Force : Frictional force always opposes the motion of one

                       surface across another surface. To experience this force, two forces have to
                       be in contact.

                       Less friction is provided by smooth surfaces and more friction by rough
                       surfaces. Walking on plane ground provides ample friction as compared to
                       walking on icy surface. This is because ice causes very less friction. So, it is

                       a good thing for ice skating and sledging.



                                                                                             Factual Study


                                                                                          If you don’t lubricate your
                                                                                          bike regularly with oil, the
                                                                                          friction in the chain and
                                                                                          axle increases. Your bike

                                                                                          will be noisy and difficult

                         Gravitational Force                      Ice Skating             to ride.


              Activity 14.1

              Aim                       :  To understand the amount of friction applied.


              Materials Required :  An empty box, thread, smooth table, sugar.

              Procedure                  :  1.  Take a box and tie a thread around the box.
                                          2.  Move the empty box on the table with the help of a thread.



              124      Active Science-4]]></page><page Index="118"><![CDATA[3.  Spread some sugar.

                                        4.  Now move the box on the table with the help of thread.

            Observation               :   You will face difficulty moving the box on the sugar spread on

                                          the table.

            Conclusion                :   More frictional force works on the table with sugar as compared

                                         to that on the table without sugar.

                 3.  Muscular Force : Muscular force is the force applied
                     using parts of the body like arms, legs, etc. For example,

                     when a weight lifter lifts weight, his arms and muscles
                     are used. Even when you lift a pencil to write or when

                     you pedal the bicycle, it requires muscular force.



            Let’s Recapitulate

                Fill in the blanks.

                1.  The force in which parts of the body are used is called _____________.
                2.  Walking on a ground needs _____________.

                3.  Walking on icy surface provides _____________.

                4.  If someone makes an effort to move an object, it is called _____________.



             Work

            When an object moves in the direction of the applied force, work is said to be done.
            We do different types of work every day. Opening a can, the lid of a jar, cutting

            paper, etc.


            Simple Machines

            Machines have made our life easy. For example, we can use a needle to stitch a
            cloth and a knife to cut anything. These simple tools have made our daily work easy.


            There are several simple machines which we use in our daily life. Let us discuss.

            Lever  : A lever helps us to move
            something heavy with less effort or to cut

            things. For example, bottle opener, pliers,
            scissors, etc.                                                                                    Opener
                                                                            Scissors



                                                                                                                   125
                                                                                             Active Science-4]]></page><page Index="119"><![CDATA[Pulley : A pulley is a machine with a
              wheel. It has two raised edges so that a

              rope or a string can run along with the                    Pulley
              wheel without dropping off. It is used to

              draw, pull or raise things. For example,
              a pulley is used to draw a bucket of

              water from the well.                                                             Pulley


              Inclined Plane : It is a sloping surface
              on which we can push an object up or

              down. For example, loading heavy                                                          Inclined Plane

              things on to a truck, is done by an
              inclined plane.


              Wheel and Axle : The wheel and axle

              allows movement of larger objects over
              a distance with less force. There are two

              wheels in the front or the back of the                                                          Axle
              vehicle with a rod between them. The                                                      Wheel

              rod is called the axle which works as a
              connector. The wheels and axle moves

              simultaneously.


              Wedge : Wedge is a triangular shaped

              tool. It has a slanting surface and a                                              Wedge
              sharp edge in front and blunt at the

              back. It is used to separate two objects.
              For example, an axe is used to cut wood.


              Screw : It is a cylindrical-shaped tool

              with a sharp edge and a blunt circular
              top. It is an inclined plane with a raised

              line around a straight rod. It is used
              to join or attach things. It is used in                                                        Screw

              furniture and doors to fix them.






              126      Active Science-4]]></page><page Index="120"><![CDATA[E nergy And Its Sources


            To perform any work, we need energy. Energy is the capacity to do work.


            Energy has various forms such as electrical, heat, mechanical, sound, light atomic

            and chemical energy. It can be converted from one form to another.









                                                                            Heat Energy
                                     Magnetic Energy
              Light
                                                                                                  Electrical Energy
                   Chemical Energy                          Sound Energy

            We get energy from food but machines use energy                        Factual Study
            from fuel, such as petrol, diesel, etc.                            The amount of energy Americans

            The natural sources of energy are:                                 use doubles every 20 years.


            Solar Energy : The energy which we get from the sun is called solar energy. Sun
            is the ultimate source of energy. Solar heaters and solar cookers are devices which
            we use with the help of solar energy. Green plants use solar energy to prepare the

            food that we eat.















                                 Solar heater                                          Solar cooker

            Wind Energy : The energy we get from moving air is called wind energy. To
            generate electricity and to draw underground water we use windmills.















                                Wind mill                                              Wind farm

                                                                                                                   127
                                                                                             Active Science-4]]></page><page Index="121"><![CDATA[Water Energy  : We get electrical energy from water. Dams are built to store
              water from rivers. Water is then allowed to fall with a huge force from a height on

              turbines. These turbines rotate and generate electricity.
















                                     Dam                                            Hydroelectric energy


              Earth : The energy we get from hot springs emerging

              from the earth is called geothermal energy.


              Renewable Sources Of Energy

              Some energy sources that are not depleted by use
              are called renewable energy. Sun, wind and water
              are examples of renewable energy sources.


              Non-renewable Sources Of Energy

              This kind of energy cannot be renewed easily and will get exhausted one day due
              to repeated use. Coal, petrol, wood, are examples of such energy sources.




              Let’s Recapitulate

                  State whether the following statements are true or false.
                  1.  Dams are built to store water to generate electricity.                                     ______

                  2.  Sun, wind and water are examples of solar energy.                                          ______

                  3.  The uwindmill is a device used to generate geothermal energy.                              ______
                  4.  Energy can be converted from one form to another.                                          ______




                     LET’S
                    REVISE                                                           Let’s Pronounce Together

                                                                                     pulley                geothermal
                •  Force means pull or push.
                                                                                     gravitational         muscular
                •  When we throw something upwards, it always falls
                   back to the earth.                                                wedge                 renewable


              128      Active Science-4]]></page><page Index="122"><![CDATA[•  Frictional force always opposes the motion of one surface across another surface.

              •  Muscular force is the force applied using parts of the body like arms, legs, etc.
              •  When an object moves by applying force, it is called work. When an object does not
                 move by applying force, then no work is done.

              •  Machines have made our life easier.

              •  To perform any work, we need energy.



            Glossary

                 •  Machines                    :   Devices which have made our life easy.
                 •  Energy                      :  It is the ability to perform work.

                 •  Solar energy                :  Energy generated from the sun.

                 •  Wind energy                 :  Energy generated from blowing wind.
                 •  Geothermal energy  :  Energy generated from the hot springs.





            Practice Time

                A. Tick the correct option.

                1.  Pull or push refers to _____________.
                     a. force                                            b. energy

                     c. friction                                         d. work
                2.  Two surfaces have to be in contact in case of _____________.

                     a. frictional force                                 b. gravitational force
                     c. muscular force                                   d. energy

                3.  If we throw an object upwards, it always falls back on earth due to _____________.
                     a. frictional force                                 b. gravitational force

                     c. muscular force                                   d. work

                4.  Our life is made easier by _____________.
                     a. machines                                         b. solar energy

                     c. wind energy                                      d. geothermal energy

                B. Fill in the blanks.
                1.  Smooth surfaces offer _____________.

                2.  The ability to do work is called _____________.

                3.  Sun is the source of _____________.
                4.  The energy we get from the sun rays is called _____________.



                                                                                                                   129
                                                                                             Active Science-4]]></page><page Index="123"><![CDATA[C. State whether the following statements are true or false:
                  1.  Friction is an opposing force which slows down the motion of an object.                   ______

                  2.  Lever is used to push things.                                                             ______
                  3.  Screw is used to join things.                                                             ______

                  4.  Machines do not help in making our work easier.                                           ______

                  D. Give one word for the following:

                  1.  If we throw a ball upwards, it falls down. It is called                            ____________
                  2.  Machine used to cut things apart is called                                         ____________

                  3.  The ultimate source of energy is                                                   ____________
                  4.  Energy which is renewed easily and does not get used up is                         ____________


                  E. Short Answer Questions.
                  1.  Write about different types of force.

                  2.  What is work?
                  3.  Write an example of friction force.

                  4.  What is renewable energy?

                  F. Long Answer Questions.

                  1.  Define different sources of energy.
                  2.  Write about gravitational force with an example.

                  3.  Explain different types of machines.
                  4.  Explain three types of forces with examples.


                  G. Look at the pictures and write the source of their energy.























                 ____________________                ____________________                ____________________









              130      Active Science-4]]></page><page Index="124"><![CDATA[____________________               ____________________                ____________________






















                ____________________               ____________________                ____________________




            Think Hard

            If someone tells you to hold a stretched rubber band for five minutes, you might get tired,

            but if you use a stick or a pencil to keep the rubber band stretched, you will not get tired.
            Why?






            Project Work

            Draw and colour all kinds of machines which you use in your daily life.




            Life Skills Activity

            Prove that you are stronger than your friend with the help of the pulley system.









                                                                                                                   131
                                                                                             Active Science-4]]></page><page Index="125"><![CDATA[Research and Development

              If an elder person and a young boy run up the stairs in the same time, which one of them
              does more work?




              Field Trip

              Plan a trip to a vegetable market or an oil depot. See how loading and unloading of heavy

              sacks and barrels is done on trucks.



                   Net Work
                •  To understand more about the relationship between work and energy, log on to https://

                   www.youtube.com/watch?v=PD7a1EWjsTc
                •  To takeup a wind speed challenge, visit http://www.sciencekids.co.nz/projects/windspeed.

                   html
                •  Study different facts on energy on http://facts.randomhistory.com/energy-facts.html





















































              132      Active Science-4]]></page></pages></Search>
