Important Announcement
PubHTML5 Scheduled Server Maintenance on (GMT) Sunday, June 26th, 2:00 am - 8:00 am.
PubHTML5 site will be inoperative during the times indicated!

Home Explore 181010033-Alpine-G4-Textbook-Science


Published by IMAX, 2020-04-08 02:52:38

Description: 181010033-Alpine-G4-Textbook-Science


Read the Text Version

2) Area marking prevents an animal from entering into another animal’s area. The food available in an area may not be enough for more than one animal to survive. In such cases, area marking helps the animals to survive better. 3) Some behaviours help animals to live in the tough weather and adjust to changes in the availability of food. For example, moving from one place to another, sleeping for a long time and so on. BENEFITS OF Different PHYSICAL FEATURES Let us see how the physical features help animals. 1) In animals like tigers and lions, the ears facing forward help to focus on the prey they hunt. In animals like rabbit and deer, the ears which move around help them to know the direction of their enemies. 2) Hair protect the animals from cold weather. The type of hair in animals depend on the climate of the place. For example, animals living in a cold region have thicker hair than those in a warm region. For the animals like fish that always live in water, their body is covered with scales instead of hair. Also, the shape of their body is such that they can swim easily. Feathers of birds cover and protect their body. 3) The trunk of elephants helps to pick up food and put it into the mouth. It also helps to take up enough water for drinking and bathing. 4) The tails of animals have different uses. For example, monkeys have long tails which help in holding on to branches and jumping from one tree to another. The tails of cats and kangaroos help them to hop and balance. Application We, humans, are social animals. Let us try to find out similarities between us and other animals. 1) Shelter: Animals find caves or build nests for their protection. Like animals, humans also build houses for protection from tough weather and harmful animals. shelters of animals house of humans Animal Behaviour 47 Science_Alpine_Grade 4_TB.indb 47 1/30/2018 2:40:27 PM

2) Living in a group: Many animals live together in groups and follow the rules of the group. We also live in small or large groups in the form of family, community or society. Like the animals, we also follow certain rules within our groups. Amazing Facts Animals like the chameleon can change their colour to match with the environment! chameleon Higher Order Thinking Skills (H.O.T.S.) Like us, animals can also smell, see, hear, touch and feel. Some senses of animals are stronger than ours. 1) A dog can hear sounds that we cannot hear. Bats can make and hear sounds which we cannot hear. It helps them while flying. As animals have a sharper sense of hearing, any loud noise can be harmful to them. For example, the sound of crackers affects them a lot. 2) Animals’ sense of smell is also many times stronger than us. The strong sense of smell helps them to protect themselves from enemies. For example, a rabbit gets the smell of its enemy even when it is far away. Animals can find food easily due to a strong sense of smell. You must have seen the expertise of ants and houseflies in finding food. 3) Animals like cats have night vision which helps them to hunt in the dark. Find out more about such senses of animals. 48 1/30/2018 2:40:28 PM Science_Alpine_Grade 4_TB.indb 48

Inside the Lab – B Make sure you do these activities only with the help of a teacher or an adult. Activity B1: Soil’s Capacity to Hold Water You will need: four empty glass jars, four filter papers, four empty plastic bottles, four different types of soil You need to: 1) cut the empty plastic bottles into half to use the top part as funnels. (Teacher should help the students while cutting.) 2) place funnels on the mouth of the glass jars. 3) fold the filter papers in cone shape, and place them inside the plastic funnels as shown in the picture. 4) fill the plastic funnels with soil as shown in the picture. Fill different types of soil in each funnels. 5) slowly add 200 mℓ of water in each funnel. 6) find out how much water was retained by the soil by looking at the amount of water falling into the glass jars. 7) We will observe that different types of soils have different capacity to hold water. Activity B2: Simple Water Filter Let us now make a simple water filter. You will need: a large plastic bottle, a container, cotton cloth, gravel, sand, muddy water You need to: 1) make about 8–10 holes in the bottom of the large, empty plastic bottle. Inside the Lab – B 49 Science_Alpine_Grade 4_TB.indb 49 1/30/2018 2:40:29 PM

2) cut off the top of the bottle evenly. (Teacher should help muddy water the students while cutting.) water bottle 3) spread the cotton cloth in the bottom covering all the sand holes. gravel cotton cloth 4) add a layer of gravel. clean water container 5) fill the bottle with sand. simple water filter 6) pour your muddy water through the homemade filter. 7) retrieve the water in another container placed under the filter. 8) look at the water that comes out of the filter. It should be clear. If not, you may have to pass the water through the filter more than once. Note: Now you have made a water filter but the water you get may not be safe to drink. The water may still contain harmful bacteria that your filter did not remove. To get water safe enough to drink, you also need to purify it. 50 1/30/2018 2:40:29 PM Science_Alpine_Grade 4_TB.indb 50

Lesson Food Storage 11 Let Us Learn About r food spoilage. u methods to store and preserve food. a benefits of storing food. h food storage during travel. Think Farha’s father cooked biryani for dinner. After dinner, he father smelling the biryani kept the leftover biryani in the kitchen cupboard. Next day, before giving the biryani to Farha, he smelled it. Then he said, “This is spoilt now. Do not eat this. You will fall sick.” What happened to the biryani? Why can’t Farha eat it? Remembering When Farha’s father opened the lid of the cooker, there was a bad smell. He also saw some yellow things on the biryani rice. Can you guess what happened to the biryani? The biryani is spoilt. When food becomes harmful for our health, we say it is spoilt. We should not eat spoilt food. We throw away the spoilt food. Food spoilage means the nutrition from food is lost. This food gets wasted. Science_Alpine_Grade 4_TB.indb 51 51 1/30/2018 2:40:32 PM

spoilt food items REASONS FOR FOOD SPOILAGE The food spoils due to the presence of microorganisms. These microorganisms grow faster in a hot climate. Example: fungi, bacteria and so on • Fungi which grow on food are of different sizes. We can see some of them with our eyes and some we cannot. • We cannot see bacteria with our eyes. IDENTIFYING SPOILT FOOD How did Farha’s father know that the biryani was spoilt? The colour, smell, look and touch of the food changes when spoilt. Spot the difference between the two bananas. Some food items that we buy from the market have the date by which the food will be spoilt. It may be given as: • use before, or fresh and spoilt banana • best before, or • expiry date We must always check this date before buying any food item. Think and write how many days the following food items will take to spoil: 1) cooked Maggi: __________________________________ 2) bread: __________________________________ 3) kurkure: __________________________________ Some food items get spoilt in few hours. Some food items gets spoilt in months. Cooked food items (like roti, curry, dal and so on) get spoilt faster than packaged food items (like biscuits, chips and so on). 52 1/30/2018 2:40:36 PM Science_Alpine_Grade 4_TB.indb 52

Understanding In olden days, people used natural methods to store and preserve food. For example, in cold places, they froze fish and meat on ice. In hotter climates, they dried food in the Sun. Food was stored in cool rivers and caves. frozen fish on ice drying rice grains under the Sun Let us see what we use today. METHODS TO STORE FOOD We need to store all types of food items to use them later. Storing food for later use is called food storage. It is important to store food properly to avoid the wastage of food. Think and write where we store the following food items. 1) milk: ______________________________________________________________________________ 2) dals: _ ______________________________________________________________________________ 3) apples: ____________________________________________________________________________ 4) onion: ________________________________________________________________________________ 5) leafy vegetables : ____________________________________________________________________ Different types of food items are stored in different places. Some in the refrigerator, some in a cool and dry place, some in dry food containers and so on. dry food in containers different food items stored in a fridge Food Storage 53 Science_Alpine_Grade 4_TB.indb 53 1/30/2018 2:40:42 PM

METHODS TO PRESERVE FOOD Storing food ensures that food is fresh, healthy and maintains its nutrient value until we use them. The steps we take to keep the food fresh and nutrient rich is food preservation. Look at the pictures below. Write the names of the food items that you see in the pictures. 1) Hint: This is made from many fruits and vegetables. This dish made from mango is very famous. p _____________________________________________________________________________________ 2) Hint: We put this food item on bread. It is sweet in taste. j ______________________________________________________________________________________ We make pickles to preserve fruits like mangoes, drying in the Sun deep freezer lemons and vegetables like carrots using salt. Mangoes, apples and other fruits are preserved as jam using sugar or jaggery. Some food items like chillies and grapes are preserved by drying them under the hot sun. Some food items like peas, meat and ice creams are frozen in the deep freezer. Application As explained earlier, people preserve food so that it can be consumed later. But there are other reasons for preserving food as well. 54 1/30/2018 2:40:44 PM Science_Alpine_Grade 4_TB.indb 54

• Due to preservation, the food items become available throughout the year. Some fruits and vegetables are seasonal. We can get them in another season due to preservation. For example, mangoes are summer fruits. If we want to enjoy them in winter, we can have canned juice, jams and jellies. Also, we can store them as pickles. • Sometimes, preservation methods add nutritional value, texture and flavour to the food items. For example, adding a large amount of sugar in the fruit pulp makes it tastier to eat. It preserves the fruit pulp at the same time. Example: aamras Amazing Facts honey Honey is one of the food items which mostly does not spoil. It does not allow microorganisms to grow in it. So, it lasts for years without getting spoilt. Higher Order Thinking Skills (H.O.T.S.) When we go for a picnic or a long vacation, we take some food with us. What kind of food do we take? Some tips to prevent food spoilage while travelling are: 1) Choose dry food items which do not spoil easily. Example: nuts, chips, dry fruits, biscuits, chiwda, sev and so on. 2) Pack food items carefully to prevent water from getting in. We can use foils, papers and plastic wraps to pack sandwich, roti, paratha, dosa, idli and so on. 3) We should not pack food items when they are hot. family picnic We must cool them first. 4) We should keep the food in a cool place, away from sunlight. Food Storage 55 Science_Alpine_Grade 4_TB.indb 55 1/30/2018 2:40:47 PM

Lesson Building Materials 12 Let Us Learn About R different building materials and tools. u how bricks are made. a houses – then and now. h bhunga. Think Reena went with her father to see the construction of their new house. What all things will she see there? Can you guess? Remembering wooden house Materials used to build houses 1/30/2018 2:40:49 PM Building a house requires different materials and tools. The materials used for building houses differ from place to place. They depend on the climate, availability of materials and cost. The tools used depend on the type of house being built. Let us look at some of the different materials and tools. 56 Science_Alpine_Grade 4_TB.indb 56

1) Wood: Wooden houses are found in areas where the climate is cold, and wood is available in plenty. Wood does not allow heat to pass through it. So, the wooden houses remain warm in the cold climate. 2) Stone: In regions with hot climates, houses are made of stone. Stone keeps the houses cool by keeping the heat out. 3) Glass: Another material that we now use is glass. Glass makes the house look more airy and spacious. It also lets in natural light so that extra lighting is not needed during the day. stone house glass used in construction Today, we mostly use sand, bricks, wood, iron, stones, cement and concrete to build our houses. Concrete is a mixture of sand, cement, water and small stones. Materials used for construction sand bricks wood metal rods concrete We also use different types of paints to paint the houses. Paints protect the walls and make them look beautiful. People such as architects, engineers, masons and carpenters are involved in constructing a house. Engineers and architects create the design and layout of a house. They also decide the type of building materials to be used. A mason cuts and lays the stones of the building. A carpenter does all the woodwork. They use different types of tools. Some of them are given below: tools used by a tools used by an tools used by a tools for carpenter construction mason engineer and architect Building Materials 57 Science_Alpine_Grade 4_TB.indb 57 1/30/2018 2:40:50 PM

To build a house, we may also need machines like the bulldozer, concrete mixer, crane and so on. Machines used for construction bulldozer concrete mixer crane Understanding Do you know how bricks are made? Bricks are mostly made of clay or concrete. Here are some of the steps used for making bricks out of clay: 1) Preparing clay: Water is added to the clayey soil. Mixing is done to make the clayey soil smooth and uniform. 2) Moulding: Hand moulds are used to shape this wet mixing brick clay with water clay to form bricks. Nowadays, machine moulds are also used to make bricks. making bricks using moulds 3) Drying: After moulding, the bricks are allowed to slowly air-dry in the open. 4) Firing: The dried bricks are hardened using fire. For this, oven like kilns (bhatta or bhatti) are built in the open fields using the dried bricks. Then this kiln is heated using fire. It takes two weeks for the kiln to cool down after firing. After the bricks are fired and cooled, they are unloaded from the kiln and packaged and stored. 58 1/30/2018 2:40:52 PM Science_Alpine_Grade 4_TB.indb 58

bricks are dried in the open bricks are fired in a kiln Application Houses today have tube lights, bulbs and fans. What about the days when there was no electricity? How did the kings and Maharajas build their huge buildings? Maharajas built forts. Forts are large buildings that used to provide houses for thousands of families. They used to build forts on top of hills to protect themselves from enemies. Let us look at one fort closely to see how they were built and how different it is from the houses we build today. Mehrangarh Fort in Jodhpur, Rajasthan The Mehrangarh fort is one of the biggest forts in India. It has thick, strong walls. The thick walls of the fort kept the rooms cool and protected Mehrangarh fort the people from the hot desert sun. It has several courtyards with lots of windows. The fort did not have electricity and fans. Did their rooms not get hot? No, the ceilings of the rooms were usually very high. Near the roof, there were small windows. They allowed fresh air to flow within the rooms. The presence of sunlight and flow of fresh air ensured hygienic conditions inside. This is important to prevent diseases. Many open cut-outs allowed the air to flow freely. interior of the Mehrangarh fort Building Materials 59 Science_Alpine_Grade 4_TB.indb 59 1/30/2018 2:40:56 PM

What are the things in your house that keep it cool or warm, well-lit or shaded? Some of them are given below: 1) curtains 2) a terrace or a veranda 3) walls 4) the arrangement of the windows and the doors in the house Discuss with your friends how each one helps us. Amazing Facts The Indian Kings used to live in palaces. Palaces were luxurious homes. It is said that some of these Maharajas used gold, silver, gems like diamond and so on to build and decorate their palaces. a palace Higher Order Thinking Skills (H.O.T.S.) Let us look at a special type of house called the Bhunga. It is a type of house that is built by the people in the Kutch district of the Gujarat state in India. The Bhunga is like a cylinder in shape with a cone-like roof. It has a door and two windows. Even though it is a kaccha house, it does not collapse Bhunga house even during an earthquake. In fact, when the last Kutch earthquake occurred, many pucca houses fell down, but these remained. How is this possible? The cylindrical shape, height of the roof and its conical shape give it the strength to survive ground shakes. 60 1/30/2018 2:40:57 PM Science_Alpine_Grade 4_TB.indb 60

Lesson Types of Cloth 13 Let Us Learn About r different types of cloth material. U making cloth from fibres. A colouring and printing of cloth. H taking care of clothes. Think Elena got a beautiful silk frock as a birthday gift from her aunt. It was soft and smooth to touch. She wondered why the clothes we wear look and feel different. Why some clothes were rough while some others were smooth? Remembering Based on the season and occasion, we wear different types of clothes. The look and feel of the clothes are different. Some of them make us feel warm. Some keep us cool. Some are smooth and shiny. Clothes look and feel different because of the differences in the material used to make them. They are made up of fibres. Fibre is thin like hair. You will see these fibres at any tailor’s shop. Fibres are of two main types: Science_Alpine_Grade 4_TB.indb 61 61 1/30/2018 2:40:58 PM

1) Natural fibres: These are obtained from natural resources. They can be plant fibres or animal fibres. A few examples of natural fibres are cotton, jute, silk and wool. Cotton and jute are plant fibres while silk and wool are animal fibres. Wool is obtained from the fleece of sheep or goat. We also get wool from the hair of rabbits, yak and camels. Silk fibre is drawn from the cocoon of silkworm. cotton fibre jute fibre silk fibre wool fibre nylon fibre 2) Artificial (synthetic) fibres: These are human-made fibres. Example: nylon, rayon. When artificial fibres are thrown after use, they do not breakdown under soil like natural fibres. Hence, they are harmful to the environment. We must avoid using them. Understanding Now we know our clothes are formed from fibres. But how do we make clothes from fibres? Cotton and jute are most widely used natural fibres. COTTON CLOTH FROM COTTON PLANT Cotton plants are grown in places with long, hot and dry summers. They need plenty of sunshine to grow. The flowers develop into green fruits (pods) with seeds in them. White, soft, fluffy fibres of different lengths grow around the seeds to form bolls. cotton flowers cotton pods cotton bolls 62 1/30/2018 2:41:07 PM Science_Alpine_Grade 4_TB.indb 62

Let us see the steps to make cotton cloth from a cotton plant. 1) When the pods burst open, we can see the fibres inside. The bolls are then collected from the plants. 2) The cotton picked from the plants has seeds in it. 3) The seeds of cotton are separated using a machine. Then, it is fed into a machine to comb and straighten the fibres. 4) The fibre is then spun into yarn using spinning machines. The yarn is a continuous thread formed by grouping and twisting the fibres. We also do this at home while making wicks for oil lamps. machine separating spinning machine hand spinning seeds from cotton bolls 5) Weaving is done by passing the threads or yarn over and under each other to make a cloth or fabric. 6) The cotton fabric is cut and stitched into different types of clothes we wear. JUTE CLOTH FROM JUTE PLANT weaving Jute is grown during the rainy season. Jute is mainly grown in West Bengal, Bihar and Assam in India. To make the jute fibre, the stem of the jute plant is soaked in water for 2 to 3 days. Then it is pulled out and dried. The fibres are then woven into threads and ropes. These threads are used to make jute clothes and gunny bags. Application Clothes look beautiful and different due to different colours and patterns on them. The fabric is coloured through dyeing and printing. dyeing printing Types of Cloth 63 Science_Alpine_Grade 4_TB.indb 63 1/30/2018 2:41:07 PM

In printing, multiple colours are used to make patterns on the fabric. Dyeing can be done before weaving the yarns into fabric using single or many colours. Natural dyes and chemical dyes are used to colour the clothes. Natural dyes Synthetic dyes • from animals and plants • from chemicals Examples: flowers and roots of plants, Example: mauvine (It is the first synthetic vegetables chemical dye that was unexpectedly discovered in 1856.) Different methods are used for dyeing and printing clothes. Let us see some of them: Mixing colours: Attractive clothes are made by mixing the colours while dyeing. Different types of colour combinations are used to make them prettier. Block printing: A block of wood with a fabric dyed with mixed colours specific design is used for this. The block is dipped in dye and pressed on the cloth to be printed. The same process is repeated several times to get a beautiful pattern on the cloth. It is one of the oldest methods of fabric printing. We can also do block printing using a potato (or any other vegetable). Take a potato, cut it into two pieces, carve block printing any design you like on the piece. Your ‘block’ is ready. Dip it in water colours. Take a small piece of old cloth, block prints using vegetables handkerchief or a paper. Press the block on it. You can repeat it to get the design of your choice. You can also use vegetables like ladies finger or cut capsicum for this. 64 1/30/2018 2:41:08 PM Science_Alpine_Grade 4_TB.indb 64

Amazing Facts Nearly 50,000 silkworms are killed to make one silk saree. Kusuma Rajaiah, of Hyderabad, has come up with a method to produce silk without killing silkworms. Kusuma Rajaiah displaying a silk saree Higher Order Thinking Skills (H.O.T.S.) Taking care of clothes is important to make them look better and help them last longer. Let us see how to take care of clothes. We need to follow the instructions written on the tag of clothes. Cotton and synthetic clothes should be washed well with a good soap or detergent to remove all the sweat, dirt and stains. They should be dried carefully. Drying dark coloured clothes in direct and bright sunlight for too long can make the colours dull. Ironing clothes makes them wrinkle free. Woollen and silk clothes need a lot of care. drying and ironing clothes They should be dry-cleaned or washed gently with cold water. They are easily attacked by small insects like moth and silverfish. We should store silk and woollen clothes with mothballs or dried neem leaves. These will keep the insects away. Types of Cloth 65 Science_Alpine_Grade 4_TB.indb 65 1/30/2018 2:41:09 PM

Lesson Fuels 14 Let Us Learn About R fuels and their types. u motor fuels. a ways to save fuel. h renewable and non-renewable fuels. Think car We get energy to work from the food we eat. Look at the given pictures. Where do these vehicles get the energy to run? Is the source of energy the same? cycle rickshaw Remembering FUELS We have learnt that we get the energy to work from food. Vehicles get energy from fuels. A fuel is a material which provides energy to move or work. We use different types of fuels in our day-to-day life. Let us learn about different types of fuels. 66 1/30/2018 2:41:10 PM Science_Alpine_Grade 4_TB.indb 66

TYPES OF FUELS Fuels can be in solid, liquid or gaseous form. 1) Solid fuels: Firewood, cow, dung cakes and coal are examples of solid fuels. 2) Liquid fuels: Petrol, diesel, kerosene and LPG are some liquid fuels. 3) Gaseous fuel: Coal gas, natural gas, LPG cylinder coal Compressed Natural Gas (CNG) are examples of gaseous fuels. We have seen fuels and their types. But where do these fuels come from? Most of the fuels we use are present in nature. Let us learn more about some natural fuels. FOSSIL FUELS Some fuels are found in the deeper layers of soil. They are a mine formed by the decay of dead organisms. When dead plants and animals get covered by heavy layers of soil, they change into fuels. These fuels are called fossil fuels. Formation of fossil fuels takes thousands of years. Example: petroleum (crude oil), coal and natural gas Fossil fuels are dug out from under the ground through mining. A mine is a hole or tunnel dug into the ground to take these raw fuels out. We make fuels like petrol, diesel, kerosene and LPG from petroleum. We use fuels for various purposes like cooking, transport and running machines in factories. 1) For domestic use, we use wood, coal, kerosene, cow dung cakes and LPG. 2) We use coal, diesel and petrol for road, sea and air transport vehicles. 3) Coal and natural gas are used in factories. Understanding The fuels used to run vehicles are called motor fuels. Motor fuels give energy to the vehicles to run. From where do we get the motor fuels for our use? Have you seen a petrol pump? We get the motor fuels from these pumps or fuel stations. petrol pump Fuels 67 Science_Alpine_Grade 4_TB.indb 67 1/30/2018 2:41:11 PM

Have you seen different coloured nozzles at a petrol pump? What do these colours mean? There are different types of motor fuels for which there are different coloured nozzles at the petrol pump. Find out which colour means which fuel. The following are some motor fuels: 1) Gasoline or petrol is the most common fuel used in cars and two-wheelers today. 2) Diesel is widely used in trucks, boats, buses and so on. 3) CNG is used to run cars, auto rickshaws or buses. 4) LPG can be used in certain vehicles. It is also used at our homes for cooking. What about other vehicles like trains, boats and aeroplanes? • Trains run on diesel or electricity. • Boats and ships with power engines mostly use diesel as a fuel. • Aeroplanes use petroleum fuels. Application The number of vehicles is increasing day by day. They all need fuel to run. Fuels are limited in supply and will one day be over. So, we need to use fuels carefully without wasting them. The different ways in which we can save fuels are: 1) switching off vehicles at signals. 2) getting our vehicles repaired regularly. 3) not using vehicles for walkable distances. 4) using public transport vehicles like buses. By taking these small measures, we can save a lot of fuel every day. Do you have a vehicle at your home? Do you go with parents to the petrol pump to fill petrol in it? Do you know how much a litre of petrol or diesel cost per litre? Try to find out if the cost is same or it differs in different areas, cities, states or countries. We have learnt that fossil fuels are used as motor fuels. What are the other uses of fossil fuels? They are used to make many products like plastics, synthetic fibres, medicines and beauty products. Find out some products made from crude oil. 68 1/30/2018 2:41:11 PM Science_Alpine_Grade 4_TB.indb 68

Amazing Facts The Gevra coal mines in Chhattisgarh is the largest coal mine in India and Asia. It is world’s second largest coal mine. It was opened in 1981. Gevra coal mines Higher Order Thinking Skills (H.O.T.S.) We have learnt that most of the fuels we use are derived from fossil fuels. But, these fuels are in limited quantity. They cannot be produced easily, as their formation takes a long time. They may get over some day. So, they are called non-renewable fuels. Example: fossil fuels (coal, petroleum, oil) and natural gas Some fuels can be produced in a short span of time. The materials required to produce them are continuously available to us. Such fuels are called renewable fuels. For example, biofuels. Biofuels are renewable fuels made from plant and animal materials. Some examples of biofuels are: 1) biogas prepared from animal waste 2) biodiesel prepared from vegetable oils Biofuels are also known as green fuels, as they burn without causing air pollution. Fuels 69 Science_Alpine_Grade 4_TB.indb 69 1/30/2018 2:41:12 PM

Lesson Ways of Communication 15 Let Us Learn About r different ways of communication. u how different ways of communication work. a the benefits and problems of ways of communication. h making my own ways to communicate. Think How do we know what is happening in the neighbouring states and countries? If scientists have discovered a new planet or if it is going to rain today, how do people get to know about it? news channel on TV Remembering Look at the pictures below. Do you know what these are? What are they used for? ____________________ ________________ _________________ __________________ 70 1/30/2018 2:41:14 PM Science_Alpine_Grade 4_TB.indb 70

Communication occurs when we pass information from one place to another. To do this, we use newspaper, TV, radio, internet and so on. These are ways to share information. Communication can be between a few people or many people. COMMUNICATION WITH MANY PEOPLE Let us play a game. Make one chit with the name of your favourite cartoon. Pass it on to a friend sitting away from you, without getting up from your place. Did your friend sitting farthest from you get the chit? Communication can be in the written form, audio form and video form. Think of one example of a way of communication in: 1) written form: _________________________________________________________________________ 2) audio form: _________________________________________________________________________ 3) video form: _________________________________________________________________________ COMMUNICATING WITH FEWER PEOPLE Can you tell what is happening in the picture? Sometimes we don’t want to give or pass some information to everyone. We want to give it to only one person or a few people. How do we do that? To communicate to fewer people, we use some other ways. For example, letters, telephone, emails and so on. letters and postcards telephones e-mails Ways of Communication 71 Science_Alpine_Grade 4_TB.indb 71 1/30/2018 2:41:16 PM

Understanding We have seen different ways to communicate. Now let us see how some of them work. WRITTEN FORM – Letters, Postcards and E-mails Let us see how the letters are sent and received. 1) The person who wants to write a letter may use a postcard, an inland letter or a separate paper with an envelope. postcard inland letter envelope with letter 2) People need to write the address of the person to whom a letter with stamps on it the letter is to be sent. They must paste a stamp next to the address. 3) Then, they put the letter in a nearby post box. 4) From the postbox, it is carried to the nearby post office. postbox post office 5) At the post office, the letters are sorted as per the addresses on them. Do you know what happens next? We can also send packets or boxes. Nowadays, many courier services also do the same type of job. 72 Science_Alpine_Grade 4_TB.indb 72 1/30/2018 2:41:18 PM

Can you name some courier services near your home? These days, we mostly send letters through the internet as e-mails. They reach within seconds. AUDIO FORM – Mobile phones Did you ever make paper boats? How do they go from one place to another? Imagine you throw a small rock in a pool. What happens? It causes waves or ripples to go out in paper boat water waves in a pond all directions. Radio waves are like water waves. Our mobile phones send out radio waves just like the small rock sends out water waves. The radio waves go in all directions until they hit a mobile phone tower. The tower will then send a radio wave to the person you want to talk to. signals from a tower Application Imagine the world without telephones, televisions and computers. We use them every day. They make our lives simpler. But they may sometimes lead to problems. Let us see the benefits and problems of communication in detail. BENEFITS 1) They help us to stay in touch with our family and friends. 2) We can learn new things from the internet using Google, Yahoo!, Wikipedia and so on. We can use them in studies. Use of internet has now become the easiest and fastest way to communicate. Do you know about Facebook and WhatsApp? How do they help us? PROBLEMS We should also use the communication media carefully. 1) Spending lots of time on the mobile phones, computers or TVs may cause health problems. For example, the bright screens of these may harm our eyes. Earphones that we use may be harmful to ears. Ways of Communication 73 Science_Alpine_Grade 4_TB.indb 73 1/30/2018 2:41:19 PM

2) Spending more time playing video games or using phones, laptops and so on rather than playing outdoors is bad. We do not get enough exercise. This affects our growth and health. Amazing Facts Do you know the e-mail addresses have a symbol @ as a part of them? This symbol was first used in 1971. This helped the messages to travel from one phone, laptop or computer to another. Do your have an e-mail ID? Write it below. _____________________________________________________________________ at symbol If not, then create an e-mail ID for yourself. Write it above. Most often, people use their names in their e-mail IDs. But you may write anything as your e-mail ID. Higher Order Thinking Skills (H.O.T.S.) Did you know, in olden times people used drums and smoke signals to communicate? Then, they learnt to write. Written messages were sent using birds like horse riders, runners or birds like pigeons. People in olden times also communicated through pictographs, cave paintings and so on. drums smoke signalling messenger pigeon People made their own ways to communicate. Look at the picture given. What are the kids doing? Discuss with your friends. If you have to make your own way of communication, what will it be? 74 1/30/2018 2:41:23 PM Science_Alpine_Grade 4_TB.indb 74

Lesson Force and Work 16 Let Us Learn About R force. u types of forces. a work done. h activities where work is not done. Think Rahim was playing cricket. Every time after hitting a six, the ball comes back to the ground. He wondered, why all things fall downwards always? batsman hitting a six things falling downwards Remembering Non-living things around us cannot move on their own from one place to another. How do we make them move? We either push or pull them. push pull Science_Alpine_Grade 4_TB.indb 75 75 1/30/2018 2:41:27 PM

Look at the given pictures. To move a trolley, we need to push or pull it. This pull or push to make an object move is force. We also need force to stop a moving object. What do we do to stop a bicycles while riding it? We use the brakes. Through the brakes, we are putting force to stop the wheels from pulling a trolley pushing a trolley rolling. Force is also needed to change the direction of a moving object. When we put more force (push or pull), objects will move faster. When we put less force (push or pull), objects will move slower. Try this: 1) Press against a plastic bottle. Its shape will change. put on force to stop a bicycle We can also change the shape of any object by applying a force. 2) Pull the two edges of the paper in the opposite direction. It will get torn. 3) By pressing a fully blown balloon, it bursts. We can tear or break objects by applying force. What can a force do? 1) A force can make an object move. 2) A force can make a moving object stop. 3) A force can change (increase or decrease) the speed of a moving object. 4) A force can change the direction of a moving object. 5) A force can change the shape of an object. Understanding You have learnt that we apply force to move, stop or change the shape of things. Some forces are acting all the time in nature. Let us learn about them. GRAVITY Sometimes, objects may move or stop without anyone applying any push or pull. For example, rain. Do we pull the raindrops towards the ground? No, they are pulled towards the ground by some other force. In the same way, the ball that we throw up comes back without raindrops ball thrown up anyone pulling it. The force that pulls objects towards the Earth is comes down called gravity. 76 Science_Alpine_Grade 4_TB.indb 76 1/30/2018 2:41:30 PM

FRICTION We have learnt that force is needed to stop a moving object. Now, roll a ball slowly. After some time, the ball stops rolling on its own. Think, when your bicycle’s tyre goes flat, is it easy to pull the cycle to reach home? Why is it so tough? It is because of friction. Friction is a force that stops the movement of two things flat tyre of the bicycle touching each other. Friction can be thought to be caused by bumps on two things. On smooth surfaces, things move longer distances. On rough surfaces, the movement stops soon. This is because things with a rough surface cause more friction. When we hold anything with our hands, there is friction acting between our fingers and the object. Due to the friction, the object does not slip out of our hand. Friction helps us hold things tight. Have you noticed that oil on our hands makes it more slippery? Oil forms a layer over the surface and reduces its roughness. So, the friction becomes low. Application When we apply force on an object to move it, stop a moving object or change its shape, we do work. For example, we pick up a box from the ground. The box moves from its original position. The force we put on the box made it move. So, we did work. When we hit a ball using a bat, the force lifting a box hitting a ball with a bat we apply makes the ball move to another position. So, we can say that some work is done. Amazing Facts Have you observed that tyres of vehicles have grooves and spikes in them? This is to make the surface rough and increase friction. Tyres with good friction prevent skidding while you apply the brakes. tyre with a rough surface Force and Work 77 Science_Alpine_Grade 4_TB.indb 77 1/30/2018 2:41:34 PM

Higher Order Thinking Skills (H.O.T.S.) In our daily life, we do many activities and say that we have done some work. But in science, work is not done in every activity. Here are a few pictures. Identify the objects that are moving and those that are not moving. Tick mark the pictures where some work is done. Work is done when things move from their place. falling leaf moving car girl sitting with books on her head Measuring work can sometimes be tricky. For the work to be done, the pushing the wall position of the object should change from one point to other. If you push the wall with all your energy but the wall doesn’t move, no work has occurred. This is because the wall did not change its position. Sometimes, we may apply a lot of force to move something. But if things don’t move on putting force, then it means that no work is done. 78 1/30/2018 2:41:38 PM Science_Alpine_Grade 4_TB.indb 78

Lesson Forms of Energy 17 Let Us Learn About R energy and its sources. u forms of energy. a uses of energy. h saving energy. Think We need energy to do any work. We get energy from the food we eat. Have you ever wondered what energy is? Where does this energy come from? Remembering Do your parents tell you to drink milk or eat vegetables to get boy kicking football with force energy? We hear the word energy often. What do you do to kick a football? We have learnt in the last lesson that we need force to move, stop or change the shape of an object. We put force on the ball to move it. To put force, we need energy. So, all types of forces have some energy linked with them. Science_Alpine_Grade 4_TB.indb 79 79 1/30/2018 2:41:41 PM

Where does the food we eat get the energy from? The Sun is the basic source of energy plants using solar energy kid eating food for energy on the Earth. The energy we get from the Sun is called solar energy. We can feel the solar energy in the form of light and heat. Plants use this energy to make their food and store it in different plant parts. Some energy is used for the growth of the plant. When we eat plant parts, we get the energy stored in plants. Other than Sun, there are some other energy sources. Let us recall what they are: • Where do vehicles get the energy to run? They get the energy from fuels. • The wind is another source of energy. • Moving water is also an important source of energy. fuel as energy source trees swaying due to the wind flowing water as an energy source Some sources of energy like the Sun, wind and water are not limited, while other sources like fuels are limited. They may get over someday. We must save all kinds of energy sources. Think, can we hold the energy in our hands? Try to hold the wind energy or hold the running water from the tap. We cannot hold energy. Energy has no shape. Understanding We have learnt that we get energy from different sources. Now, let us learn about different forms of energy using some examples. 80 1/30/2018 2:41:46 PM Science_Alpine_Grade 4_TB.indb 80

1) Do you find any difference between day and night when there are no bulbs or tube lights? It is the presence of light. When you go to the theatre to watch a movie, is it easy for you to find your seats? It is dark until the movie starts. Light is the form of energy we can see. 2) Rub the palms of your hands 10–15 times. Now, quickly theatre with few lights touch your eyes with your palms. What do you feel? We can feel the warmth. This form of energy is heat. 3) Try blowing on a notebook from the side. What happens to the pages of the notebook? Think, about what you do when you want to blow a balloon. The wind energy from your mouth made the pages move and the balloon expand. rubbing the palms place palms on eyes wind used to blow a balloon 4) Look at the electric bulbs and fans in your classroom. Where do they get the energy to work? They use electricity or electrical energy. 5) Throw your eraser slowly towards the roof. Did it stop near the roof or the floor? Gravity pulls everything down. Application We need energy to do work, whether sitting, standing, running or sleeping. We need energy: • for our body to do different work. • to light up bulbs, tube lights and so on. • to use phones, televisions, computers and so on. • to cook food. • to cool or heat homes and offices using fans, heaters and coolers. • to run vehicles. Forms of Energy 81 Science_Alpine_Grade 4_TB.indb 81 1/30/2018 2:41:52 PM

Amazing Facts Have you seen lightning during the rainy season? It is the natural form of electricity. It is very powerful. It can burn everything on its way. During lightning, we should avoid standing under a tree. lightning Higher Order Thinking Skills (H.O.T.S.) It is important to save or conserve energy. Some of the easy ways to save energy are: 1) Turn off fans, lights and other electrical devices when not in use. 2) Lots of energy is used in making paper and plastic. So, we should recycle these things to make newspapers, bottles and so on. We should not waste paper from our notebooks. We should also try to use less plastic. We should use jute and paper bags instead of plastic bags. 3) We should use renewable energy more than non-renewable energy. 82 1/30/2018 2:41:52 PM Science_Alpine_Grade 4_TB.indb 82

Inside the Lab – C Make sure you do these activities only with the help of a teacher or an adult. . Activity C1: Building a Shelter You will need: chart papers, cardboard boxes, coloured/crepe papers, crayons or colour pencils, glue or tape You need to: 1) Make groups of students, and provide them with cardboard boxes. 2) They need to build a model shelter using the materials provided. 3) For making a shelter using cardboard boxes, the following steps can be helpful: Step 1: Take a cardboard box. Step 2: Draw the outlines for doors and windows on it. Step 3: Cut the doors and windows, and stick craft paper as you need. (Teacher should help the students while cutting.) Step 4: M ake a roof for your cardboard house by cutting small pieces of cardboard as shown in Step 4. Step 5: You can make different types of houses as shown in Step 5. step 1 step 2 step 3 step 4 step 5 Science_Alpine_Grade 4_TB.indb 83 Inside the Lab - C 83 1/30/2018 2:41:52 PM

4) For building a shelter using chart papers, you can use the following steps: Step 1: Draw the outline of the house on the chart paper. Cut the paper on the borders. (Teacher should help the students while cutting.) Step 2: Fold the paper on the outlines. Step 3: Cut the windows. Step 4: Stick the border as shown in Step 4. Step 5: Paint it or use craft papers to decorate this shelter. You can even put lights in it. step 1 step 2 step 3 step 4 step 5 Activity C2: Power of Solar Energy Let us use sunlight and a magnifying glass to make fire. You will need: paper, small pieces of dry wood, a magnifying glass, a bucket of water to put out the fire You need to: 1) take a piece of paper to an open ground where you get bright sunlight. (Carefully select a place where the fire cannot spread and burn anything else) 2) take a small piece of dry wood, and place the paper over it. 3) hold the magnifying glass in such a way that the sunlight falls on it and all the light is focused on the paper. A small, bright dot will appear on the paper. 4) wait for some time. After a while, you can see that the paper catches fire. 5) put off the fire as soon as it ignites by pouring water on it. (Take help from the teacher.) 84 1/30/2018 2:41:54 PM Science_Alpine_Grade 4_TB.indb 84

Like this book? You can publish your book online for free in a few minutes!
Create your own flipbook