I Explore (H.O.T.S.) On farms, farmers grow so many plants. They may grow more than one set of plants in a year. They will repeat this practice year after year. If the same types of plants grow in the soil for many years, some soil nutrients may get completely used up. Some nutrients, which are not used by that type of plant, may pile up in the soil. Moreover, the farmers use some chemicals to increase the growth of plants. They also use chemicals to kill harmful plants and insects on the farm. These chemicals will kill even the useful organisms in the soil like earthworms. In these ways, farmlands may change into wastelands over the course of time. Some plants need a lot of water to grow. So growing such plants in huge numbers may lead to water shortage in that area. So, it is important to grow plants without harming the environment. How can we do that? 1) Some farmers do not use chemicals on their farms. They use plant and animal made materials to increase plant growth and reduce the harmful insects. For example, they use animal waste like cow dung, ash and plant waste like fallen leaves of trees to add nutrients to the soil. They use manure made of all these things. Farmers spray juice of the leaves of some plants like the neem to kill insects. 2) Another practice is to grow different plants in the same field one after the other. For example, in rice fields, after the harvesting of rice, they will grow vegetables like peas, cucumbers, pumpkins and so on. This helps to keep the nutrients in soil at a proper level. 3) In areas where there is less water, choosing plants that need less water will be helpful. Connect the Dots Social Studies Fun Humans started farming around 10,000 years ago. India is one among those countries where farming was started. So, Indians have 10,000 years of experience in farming! Food Production 47
Maths Fun In a farm, fruit trees are planted in rows. One row has 45 trees. There are 35 rows of trees on the farm. How many trees are there in all? A Note to Parent Visit a nearby farm. Let your child see the types of work happening on a farm. Also, help them identify the plants and animals grown there. 48
Lesson Forests as Shelter 9 I Will Learn About R different types of forests. U life in the forests. A the uses of forests to living things. H the need to protect the forest cover of the Earth. I Think One day Samarth found a beautiful bird’s picture in one of the magazines his father bought for him. His dad told him that the bird could not be found in cities. It lived only in forests. Also, he promised to take him to a forest someday. Do you know what a forest is? I Remember forest with cone shaped trees When we travel to different places, we may see some lands that are covered with many trees and plants. These trees are not grown 49 by people. They just grow on their own. These are forests. Forests are lands with many trees. There are different types of forests on the Earth. For example, forests found in cold mountains have cone shaped trees with needle-like leaves. Forests which grow in warm areas with high rainfall have trees with broad leaves.
Forests which get rain throughout the year remain green always. We call them evergreen rainforests. But, in some other forests, during the autumn season, the colour of the leaves changes to yellow, orange and red and they fall off. Then, the trees grow new leaves. Forests are of different types. They look different in colour, the shape of trees, shape of the leaves and so on. evergreen rainforest forest which changes colour I Understand Have you ever visited a forest? What are the things we can find inside a forest? Let us read what Samarth found when his father took him to a forest. “Once we entered the forest, the air felt cool and fresh. We could hear the chirping of different birds and the sound of beetles. There was no proper road to walk. The guide in front of us guided us through a narrow way between the bushes. When I looked up, I could not see the sky properly. The branches beetle of trees were spread forming a cover overhead. I could find many types of birds on the trees. There was a group of monkeys on the branches of a huge tree. They were eating some berries. On one of the branches, there was a huge beehive. branches covering the sky monkeys on a tree berries beehive Suddenly I heard a rustling sound from the ground. I could see a snake crawling fast. It disappeared in the bushes. The ground was covered with leaves and animal droppings. It was spongy to walk. Using a stick, I removed some layers of leaves which covered the ground. Below them, I could find dark coloured soil. It was loose. I could find some earthworms, a snail and some other insects in it. 50
There were huge termite mounds here and there. Different types of ants and some other insects were on the ground and tree trunks. One big spider was weaving a web on a bush. Some tree trunks were covered with a spongy green growth. My mother said that they were small plants which grew only in moist places. Along with them, there were some plants with palm tree like leaves. crawling snake ground covered with leaves forest soil termite mound Many twiners were growing over the trees, and some of them were hanging from the tree branches. They were thick and strong that I could easily swing on them. There were many plants with beautiful flowers and colourful fruits. The guide told us that some of them were harmful. Then we reached a stream which flowed through the forest. The water was clean and clear. I could see the stream bed below the water. Down the stream, far away from us, there was a group of elephants. twiners with thick stems poisonous fruits forest stream elephants near the stream Then, I found a group of bats on a tree. They were sleeping, hanging upside down from the tree branches. Suddenly, a kingfisher flew down, grabbed a fish from the stream and flew away. On the other side of the stream, a woodpecker was pecking on the dried up branch of a tall tree. bats on the tree kingfisher catching a fish woodpecker on a tree Forests as Shelter 51
Far ahead of us, I found some shelters. I wondered, who lived in there. The guide told us that they were the shelters of the people who lived in the forest. They eat the fruits, seeds and roots of forest plants and the flesh of wild animals. They used the water from the stream. They spoke a different language. The guide told us that we should leave the forest before it became dark. Many dangerous animals came out during the night. So we started our journey back. On the way back, mother collected some forest soil in a paper bag. She said it would help the growth of the potted tomato plants she grew in our terrace garden.” Train My Brain 1) Name one animal that Samarth found in the forest soil. 2) Which bird flew down and grabbed a fish from the stream? I Apply You read about the living things that Samarth found in the forest. Forests are home to many humans, animals and plants. They live there helping each other. What will happen to them, if we cut down trees and clear the forest? If we cut down forests, they will lose their home. Many animals will die and disappear from the Earth. Are the forests helpful only to them? Are they useful to us too? We get honey, some fruits, gums, wood and so on from forests. Forests help to absorb the rainwater into the soil. The dead leaves of trees cover the soil. The roots of plants form a network and hold the soil. So, the soil does not get washed away during rains. Moreover, they make the soil sponge-like. A sponge absorbs all the water that falls on it. In the same way, forest soil absorbs and retains the water. You read that Samarth’s mother carried some forest soil to increase the growth of tomato plants. How does the forest soil increase plant growth? Forest soil is covered with layers of dead remains of plant and animal material. The tiny microbes which live in the soil help these materials to decay and mix with the soil. When these materials decay, many nutrients are released into the soil. These nutrients help the growth of plants. 52
You know that plants absorb carbon dioxide and give out oxygen. Forests have many trees. They all absorb a lot of carbon dioxide from the air and give out oxygen. This makes the air cool and fresh. Be Amazed sundarbans Some forests are found near the seashores. They are called mangrove forests. Sundarbans is a mangrove forest. It is the largest mangrove forest in the world. It is located on the coast of West Bengal. I Explore (H.O.T.S.) Look at the aerial view of the Amazon rainforest. It looks like a green carpet, doesn’t it? Forests form a green cover over the land. Almost three out of ten parts of the land on the Earth is covered with forests. This forest cover of the Earth helps to control the carbon dioxide levels in the air. When the the Amazon rainforest, Brazil appears like a forest cover is reduced, the carbon dioxide green carpet in the air increases. This increase in the levels of carbon dioxide may make the air around the Earth warm. So, it is important to protect the forest cover of the Earth. Connect the Dots English Fun ‘Jungle’ is another name we use for forests. The word jungle is not English in origin. It is formed from a Sanskrit word ‘Jangala’ meaning unused land. Forests as Shelter 53
Maths Fun There is one circular lake in a forest. It has a radius of two kilometres. What will be the diameter of the lake? A Note to Parent If possible, you could plan a visit to a nearby forest with your child. Help him or her identify the differences between a forest and normal land. Encourage your child to take pictures of different forest plants and animals and make a photo album. 54
Inside the Lab – B Make sure you do these activities only with the help of a teacher or an adult. Activity B1: Seed Germination We have learnt that seeds need moisture, air and the right amount of warmth to germinate and grow. Let us do a seed germination activity to find out whether the seeds need all these to germinate or not. You will need: bean seeds (15–20 per bowl), five clean and empty beakers (one for each condition), paper towels, water to wet the towels, masking tape to label the beakers You need to: 1) keep the seeds in the following conditions: How Where beaker 1 Place the seeds on a wet paper towel. in air and light beaker 2 Place dry seeds. in air and light beaker 3 Pour water in the beaker. Put seeds in the water. in air and light beaker 4 Place the seeds on a wet paper towel. in a dark place beaker 5 Place the seeds on a wet paper towel. in a refrigerator beaker 1 beaker 2 beaker 3 beaker 4 beaker 5 in air and light dark place refrigerator 55
2) make predictions about what will happen. Note them down in your observation sheet. 3) have a look at the beakers 7 to 10 days later. Note down your results in the observation table given below. The seeds of which beaker germinate? Which do not? Note: • T he seeds in the water will need to have their water changed regularly, so that mould growth does not take over. • Check once a day that the paper towel is wet. Observation table: Experiment Conditions Prediction Actual Result Actual Result number after ____ days after ____ days Activity B2: Food Web Let us create a food web using animal picture cards. You will need: • scissors • gum • chart papers • pictures of different plants or plant parts like grass, vegetables, fruits, cereals, pulses and so on 56
• pictures of animals (Example: earthworm, grasshopper, rabbit, deer, elephant, wolf, lion, tiger, eagle, frog, fish, snake, hen, crow, crane, duck, squirrel, cow, cat, dog, mouse, human being) You need to: 1) use scissors to cut the chart paper into equal sized pieces. (Take your teacher’s help while cutting.) 2) paste the pictures of animals on the chart paper pieces to make picture cards. Your game cards are ready. 3) find out how many different combinations of food chains you can form using them. For example, grass, grasshopper, frog, snake and eagle will form one chain, while plant, rabbit, wolf will be another chain and so on. 4) involve your friends too. 5) try to join the food chains to make a food web. Inside the Lab – B 57
Lesson Space Travel 10 I Will Learn About r space and spacecrafts. u astronauts, space suits and space stations. a the routine followed by astronauts in space. h how to become an astronaut. I Think On TV, Samarth saw a rocket being fired up in the sky. His father told him that it is a space mission. He wondered what a space mission is. Do you know? I Remember We know that the Earth has a layer of air around it: the atmosphere. Have you ever wondered about what is beyond the sky? Have you wondered about space beyond the Earth’s atmosphere? Beyond the atmosphere, there is an open space where there is no air. All the heavenly bodies we see in the sky are present in this space. To learn more about them, we have to travel to space. How can we travel to space and to these heavenly bodies? First, we have to travel through the Earth’s atmosphere and then through the open space beyond it. 58
We use aircrafts such as planes to travel to faraway places. Can we use these aircrafts to fly into space? We cannot. Let us see why. We have learnt that the gravity of the Earth pulls everything towards it. So, all the things that we throw up fall back to the Earth. Due to this, the aircrafts cannot fly straight up, cross the atmosphere and enter the space. So, we need high-speed rockets to throw these aircrafts out of Earth’s gravity pull. If a rocket steers through the atmosphere carrying a spacecraft, the air will rub against its walls. This will make the aircraft heat up and catch fire. So, we need special vehicles which can travel at high speeds without catching fire. These special vehicles are called spacecrafts. A spacecraft is a vehicle used for travelling in space. A spacecraft can either carry human beings or an artificial satellite. rocket spacecraft I Understand The spacecraft is very different from an aircraft. So, the pilots who fly planes cannot fly them. Special pilots called astronauts fly spacecrafts. Have you seen any pictures of astronauts? Indian astronauts Rakesh Sharma Sunita Williams Kalpana Chawla Space Travel 59
Look at the pictures of the astronauts. They wear special suits. Do you spacesuit know why? Space has no air to breathe. So, we will need oxygen supply. Moreover, in space, the sunlight will be very sharp and can cause sunburn. So we need to wear spacesuits, that help us to breathe and protect us from the harmful sunlight. The way we have airports for aircrafts to land and take off, there are space stations for spacecrafts. Currently, the International Space Station (ISS) is the largest space station in space. It is an artificial satellite orbiting the Earth. It is made in such a way that it is suitable for living in space. The people who travel into the space alight at the space station and stay there to find out more about space. the International Space Station (ISS) Train My Brain 1) Name one space station. 2) Name any one Indian astronaut. I Apply What do the astronauts do in space? What do they eat? How do they sleep? Let us find out. Astronauts have to rely on the food they carry with them. These space food items are similar to those eaten every day on the Earth. They include frozen vegetables and desserts, refrigerated food, fruits and dairy products. The menu on the ISS includes more than 100 items. Astronauts choose their daily menus long before they fly into space. There are three meals per day. Snacks can be eaten at any time. Salt and pepper are available only in a liquid form. Drinks range from coffee, tea to fruit punches. 60
space food eating in space At least two hours of a day are spent exercising. This is essential to keep fit and healthy. Astronauts spend some time on spacewalks too. Astronauts carry out some experiments and research in space. For example, the experiment to find out what will happen to the growth of plants when there is no gravity. Sleeping is a little different in space. There is no up or down. Astronauts can attach their sleeping bags to a wall or a ceiling. They can sleep anywhere as long as they do not float around and bump into something. spacewalk experiments carried out sleeping in space in space Why do astronauts travel to space and other heavenly bodies? We get to know more about the changes in the Earth’s atmosphere when we look at it from space. Space travel can help us to discover new worlds. We travel to other heavenly bodies to find whether there is life on them. Have you watched any movies that show space travel and the living things which live on other planets (aliens)? view of the Earth from space space and aliens as shown in movies Space Travel 61
Be Amazed A project named ‘Mars One’ aims to set up human colonies on the planet Mars. Mars One will begin to send one person at a time from the year 2024. Three Indians – a man and two women, have been shortlisted for the next round of selection among top 100 people! Indians shortlisted for Mars One design of human colonies for the next round on planet Mars I Explore (H.O.T.S.) We have learnt that travelling to space is different from any other travel. If you want to be one of the few people to see the Earth from space and float in a spacecraft, how do you go about it? It takes many years of study and work. To be an astronaut, we have to study and get a degree in engineering, science or mathematics. After this, we have to undergo training on flying the spacecraft, lifestyle in space and so on. We must be healthy since astronaut training can be very tiring. Astronauts from different countries may share a astronaut training mission to space. So you should be good at a common language of communication like English. Are you still interested? If so, maybe someday, you can become one of the men and women who orbit the Earth in a spacecraft, walk in space or visit Mars! 62
Connect the Dots English Fun The term astronaut is formed from the Greek words ‘astron’ meaning ‘star’, and ‘nautes’ meaning ‘sailor’. Maths Fun There are 16 sunrises and 16 sunsets, every 24 hours on the ISS. How many sunrises and sunsets can astronauts see in 120 hours? A Note to Parent Discuss space, satellites and the astronauts with your child. You can show them the photographs of various space travels conducted so far, using the internet or television channels. You may also discuss the mythological stories based on space. Talk about contributions of three women scientists from ISRO in making Mangalyaan (Mars Orbiter Mission) a success. They are Seetha Somasundaram, Nandini Harinath and Minal Rohit. To know more, watch a short film named “Snapshots from Afar”. Space Travel 63
Lesson Wildfire 11 I Will Learn About R natural disasters – wildfires. u the causes of wildfires. a the effects of wildfires. h avoiding human-made wildfires. I Think Samarth was sharing his forest visit story with his friends. Then one of his friends said that on the previous day, he had seen a forest fire on TV. He also said that a lot of people died, when the fire spread to the houses of the people who lived nearby. Sherin, another friend of Samarth, said that she had seen some places getting flooded with water. Samarth wondered how forests caught fire or land got covered with water. Do you know how these disasters happen? I Remember Nature can become harmful at times. Sometimes the ground shakes or heavy rains flood the lands. Some other times, strong winds blow off everything in their way. In some places, a hot boiling liquid flows out of the Earth (lava) burning everything. Fire may break out in forest areas. 64
All these can kill humans, animals and plants and can wildfire destroy houses, roads and so on. They are disasters caused by nature. The disasters caused by nature are of different types. Let us learn about one of the natural disasters – wildfires. A wildfire is one such disaster. We will learn about some other natural disasters in the It breaks out in forests, upcoming lessons. grasslands and so on. Wildfires are the fires which break out in the forests, grasslands and so on. In India, wildfires are very frequent. Around 20,000 wildfires occur in India every year. In the state of Uttarakhand, around 1600 wildfires broke out in 2016. Wildfires are common across the world. I Understand Now you know what a wildfire is. Do you know how it is caused? Fuel, oxygen and heat source are the three things that need to be present for a wildfire to happen. Firefighters call it a fire triangle. The dry leaves, branches and grass become the fuel. The heat of the Sun fire triangle or lightning becomes the heat source. Oxygen is present in the air. Due to the extreme heat of the Sun or lightning, dry patches of grass or leaves may catch fire. The fire may then slowly spread to nearby areas. Sparks can also be caused when dry branches rub against each other due to the wind. Sometimes wildfires are also caused by careless activities of humans. For example, people throw burning things like cigarette sticks near the roadsides or they may not put off their camp fires before they leave. In some places, when people burn their fields, the fire may spread to nearby forest areas. campfire burning straws in the fields fire may spread from a burning cigarette stick Wildfire 65
Train My Brain 1) Name any one natural disaster. 2) Name any one thing needed to cause a wildfire. I Apply If a forest catches fire, along with all the forest products, wildlife will also be destroyed. Also, the people who live in the forest will become homeless, and they will have nothing to eat. This is a great loss. The smoke that comes out of the fire will cause air pollution. This results in breathing problems for the people who live nearby. But the fires are not always bad. The fires that break out in nature have some good effects too. In the forest areas with less rainfall, the leaves shed from the trees pile up on the ground. They do not decay as there is little moisture. Forest fires help to burn the thick layers of dried leaves and branches. When they burn, they form ash. Ash is rich in nutrients. This mixes with the soil and makes it more suitable for plant growth. So during the next rain, new plants can grow better. Uncontrolled wildfires can spread and cause a lot of damage. So, we control wildfires in many ways. We use water to control small fires. But in some places, this may not be possible. Then, helicopters are used to spray carbon dioxide, which can put out the fire. When a wildfire breaks out in a forest or grassland close to where controlling wildfire we live, we have to vacate our houses. We have to move to safer places till the fire settles down. Be Amazed Wildfires occur on every continent except Antarctica as there are no forests in Antarctica! 66
I Explore (H.O.T.S.) About nine out of ten wildfires break out due to human activities. Frequent and widespread wildfires are harmful to all living things. How can we ensure that our activities are not causing any wildfire? 1) No burning material should be thrown away. We should put out the fire. 2) After lighting campfire, we should put it out completely before we leave the place. 3) While burning waste materials in fields, we should make sure that the fire does not spread to nearby areas. Connect the Dots English Fun Write two adjectives to describe a wildfire. 1) ___________________________ 2) _____________________________ Maths Fun Year Number of wildfires 2013 15 Data of wildfires in a forest is given below. 2014 6 Represent it in a bar graph. 2015 11 2016 8 A Note to Parent Discuss with your child what care we should take if we go out for camping or on a forest trail. Also, it will be a huge learning to your child if you can show him or her news reports of wildfires. Wildfire 67
Lesson Cyclones and Floods 12 I Will Learn About R cyclones. u how cyclones may cause floods. a support given to cyclone-affected people. H preparing in advance for cyclones. I Think Saif was watching TV when his father said that he needed to watch the news channel, as a cyclone alert was given by a government agency. On the news channel, they were talking about strong winds and heavy rains and showing something on a map. Saif wondered what a cyclone was. Why did the government give cyclone alerts? I Remember Let us do an activity. Take a glass of water. Add a few small sized seeds to it. Now using a spoon, stir the water. Increase the speed of stirring. What do you see in the water? In the centre, there is a depression. Around it, the water spins fast. What happens to the seeds? They are in the centre. Are they going round and round? No. They are not making any fast movements. 68
A cyclone may look like this. It has a calm centre called Cyclones are powerful spinning the eye. Around the eye, winds blow at a high speed. storms that contain strong Cyclones are formed over the ocean. They bring heavy winds and rain. They normally rains along with them. form over the oceans and move towards the land. I Understand When cyclones hit land areas, a tree uprooted by a cyclone view of a flooded area in the powerful winds destroy in Andhra Pradesh Odisha after a cyclone everything in their way. They may uproot or break the trees, blow away the roofs of buildings, displace and damage vehicles and electrical posts and so on. Cyclones push the sea water into the land. They also bring heavy rains with them. Strong rains last for hours or even days. All these lead to floods. A flood is a sudden rise in the water level making land areas submerge in water. Train My Brain 1) Where are cyclones formed? 2) What do we call the central part of a cyclone? I Apply Cyclones affect the lives of all the people living in cyclone-hit areas. Flood water may cover and wash away farms, roads, buildings and so on. It makes all the sources of water unfit for drinking or bathing. Floods may damage crops in the fields as well as stored food grains. Houses and vehicles may be damaged due to the flood waters. People may become homeless. During such disasters people need support. They need food, clean drinking water, clothes, a safe place to stay and so on. So, the government arranges rescue camps or shelters for the affected people. At the rescue camps, these cyclone-affected people are provided with food, water and clothes. Cyclones and Floods 69
Flood water may take days to drain off. temporary shelters By that time, disease-causing mosquitoes, flies and other insects may increase in number. This may lead to the spread of many diseases. Hence, medical camps are also set up to give medical support to people. Be Amazed Do you know that cyclones are given names? Some of the recent cyclones which hit India were named as Vardah, Hudhud, Nilam, Laila and so on. They are not named after any people. Naming helps the people to understand and remember the cyclones easily. All the messages related to a cyclone can be sent and received mentioning these names. I Explore (H.O.T.S.) It is not possible to control cyclones. But the damage to life and property can be reduced by preparing for it in advance. For this, we must know about an approaching cyclone in advance. These days, with the help of satellites, the government gives cyclone alerts 48 hours in advance. Then, cyclone warnings are given 24 hours in advance. Thus, the people can prepare in advance. When a cyclone alert or warning is satellites help to predict cyclones given, we should listen to the radio and television to get updates about the situation. 70
Connect the Dots English Fun The word ‘cyclone’ is formed from a Greek word ‘kukloma’ meaning a wheel. Can you find another word with Greek origin and its meaning? Maths Fun A flood in a small village damaged 348 houses. Write the number using Roman numerals. A Note to Parent Discuss with your child the precautions to be taken if any major disaster like a cyclone occurs. Show him or her news related to such a disaster on the television or the newspaper. Cyclones and Floods 71
Lesson Earthquakes and Tsunami 13 I Will Learn About R earthquakes. u causes of earthquakes and how a tsunami occurs. a harmful effects of earthquakes and tsunami and responses to them. h precautions to earthquakes and tsunami. I Think Pavan was holidaying with his family at a seaside resort. One day, early morning, suddenly the ground started to shake. His father asked them to get out of the room and rush towards the lawn. Pavan could not understand what was happening. Do you know what happened? I Remember Sometimes the ground shakes. It may move up and down and may crack open. This is an earthquake. An earthquake is a shaking of the Earth’s surface. It is a natural disaster. Earthquakes do not last for more than 30 seconds at a time. But, they may repeat. The strength of the quakes is different. Some of them are weak, while others are strong. 72
A device called the seismograph is used to measure the seismograph strength of the quake. Every year, a large number of earthquakes occur in different places in the world. In some places of the world, the earthquakes happen often. Most earthquakes happen along the edges of the Pacific Ocean. So, this area is called the Pacific ring of fire. Earthquakes are natural disasters, in which the ground shakes. They are very frequent in some places, but rare in others. the Pacific ring of fire I Understand Why do earthquakes happen? Let us find out. Let us do an activity. Take a few cardboard pieces. Arrange them on a table close to one another. Place a few pencils, pens, erasers, sharpeners and so on over it. Now, pull two adjacent cardboard pieces slightly apart. What happens to the things you kept over it? They shake and tumble. Now, push two cardboards against each other. What happens? Their edges may bend, or one of them may slide over the other. All the things over it shake and get displaced. Earthquakes happen in a similar way. The Earth has layers. The upper layers are thin and broken into pieces. They float over the inner part. While floating, these pieces may collide or move apart. This causes earthquakes to occur. Let us do another activity. Take a thin plastic tray. Fill it with water. Lift it holding the edges. broken upper layers Now, ask another person to give a light bang on the lower part of the Earth of the tray. Observe what happens to the water. Bang a little harder. Observe the changes in the water. What do you find? Earthquakes and Tsunami 73
A bang on the tray creates ripples in the water. They start from the water ripples point where we bang and move towards the edges. Now, imagine the same situation happening in an ocean. An earthquake bangs the ocean floor. Then, waves will be formed in the ocean. They travel towards the shores. Sea shores are shallow. So, the waves do not have enough space in the water to move up and down. So, they rise like huge walls of water and lash over the coast. These huge waves are called a tsunami. Tsunami is a Japanese word meaning ‘harbour wave’. Train My Brain tsunami moving towards the shore 1) What happens when the pieces of the Earth’s upper layers collide? 2) What does the word ‘tsunami’ mean? I Apply Small earthquakes can topple a few buildings and crack roads. But, big earthquakes can destroy entire cities. Every year, around 10,000 people die due to earthquakes. Deaths happen when people are trapped under fallen buildings. The tsunami formed after an earthquake can destroy entire coastal areas. The waves may travel long distances into the land. On their way, they will sweep away buildings, vehicles, roads, trees and so on. Tsunami leads to the death of many people. tsunami waves wash off buildings and vehicles 74
In 2004, an earthquake happened in the Indian Ocean. The tsunami waves formed due to this earthquake killed 2,27,898 people. It was one of the deadliest natural disasters in the world. When an earthquake and tsunami occur, government and some other agencies help the affected people. They begin the search to find people who may be trapped under toppled buildings. They set up relief camps for rescued people to stay safely. Also, they arrange for food, drinking water and clothes for these people. Doctors are there at the camps to treat injured people. After rescuing people and ensuring they are safe, the government begins the rebuilding process. Schools, roads, hospitals, houses and so on are rebuilt, if damaged, for people to go back to a normal life. Be Amazed In 2009, an earthquake happened near the Samoan islands in the Pacific Ocean. The wave formed was just 7.6 centimetres high. But, when they reached the New Zealand coast, the height of the waves was 14 metres! I Explore (H.O.T.S.) We cannot stop or control earthquakes and tsunami. But, we can prepare for them. 1) We can build houses that can withstand earthquakes. Tall buildings fall easily. One or two level houses are safer. We can make houses using light materials. Even if they tumble, they will not cause much harm to the people. 2) We should not build houses near the seashore. They should be at a safe distance from the shore. 3) During an earthquake, if we are in a building, it is important to get out of it quickly. The building may collapse, or heavy objects may fall on us. 4) We should avoid using the lifts and other electrical equipment at such times. 5) It is important to leave everything and vacate the building as quickly as possible. 6) When we get a tsunami alert, we should move out of coastal areas. Earthquakes and Tsunami 75
Connect the Dots English Fun Identify the verbs, nouns and adjectives from the following words: earthquake, tsunami, tumble, lash, strong Maths Fun If 240 earthquakes happen in a month, how many earthquakes will happen in a year? A Note to Parent Keeping a safety kit ready will help us during emergencies. Help your child prepare an earthquake safety kit to be used in case of an earthquake. water radio first aid kit prescriptions/ batteries medicine important documents cell phone cash flashlight blanket map toilet paper universal tool earthquake safety kit 76
Lesson Simple Machines 14 I Will Learn About r what simple machines are. u types of simple machines. a uses of simple machines. H the simple machines in the human body. I Think Have you ever played on a see-saw with your friend? How can it lift you up and bring you down? I Remember Have you seen people loading or unloading heavy loads from a truck? How do they do it? They use a sloping surface for this purpose, so that they can roll the load on it. Have you seen your dad or a using a slope to unload using a hammer to put in a nail carpenter putting a nail in the wall? What do they use? Why do they need a hammer? 77
Have you seen people drawing water from a well? They use a wheel and rope to pull it out easily. What do the carpenters use drawing water from a well using joining wooden planks together to put the wooden planks a wheel and rope together while making furniture? We see many examples in our day-to-day life where we use some simple devices that make our work easy. These are simple machines. Simple machines are the devices that make the work easier. These machines have few or no moving parts. They are used to apply force to move objects. We need less effort to move the objects because of them. They can do the work with less force. Following are the six simple machines: inclined plane, wedge, pulley, screw, lever, wheel and axle Lever, inclined plane, wheel and axle, pulley, wedge, screw are simple machines that help us in many ways. simple machines I Understand Let us now understand how these simple machines work and make things easier. 1) Inclined plane: A sloping or slanting surface makes an inclined plane. The slant of the inclined plane can move an object from one slope level to another. 2) Wedge: A wedge is a simple machine. inclined plane wedge It is used to separate any two objects by pushing them away from each other. 78
Wedge is also like an inclined plane. It has a slanting edge which is sharp. It can be used to lift things. Most of the times, it helps us in cutting something. Example: an axe used to cut wood 3) Screw: A screw is a type of inclined plane. In a screw, an inclined cutting wood using plane is twisted (swirled) around a rod like a road around the hill. a wedge (axe) Screws are useful for putting things together tightly. Example: screw is used to connect two wooden or metal blocks together screw twisted roads 4) Pulley: A pulley is a wheel with a rope around it. Pulleys make lifting objects easier. For example, cranes use pulleys to lift heavy vehicles and building materials. 5) Wheel and axle: Wheel and axle make work easier by reducing friction. A wheel helps things to move. The axle helps the wheel turn. Example: wheels of a bicycle and other vehicles axle wheel pulley crane using the pulley wheel and axle bicycle wheel with axle 6) Lever: Lever is a bar, rod or a platform that can move about a fixed point. The fixed point is called a fulcrum. Fulcrum is a point where the lever touches the support. A lever makes it easier to move a large load with little effort. Example: see-saw fulcrum lever kids playing on a see-saw Simple Machines 79
Train My Brain 1) Name any one type of simple machine. 2) Which simple machines make use of wheels? I Apply Simple machines are useful in many ways. We see them being used every day. Let us look at some examples in our day-to-day life. Inclined plane: The staircase we use to climb and the ramp used to carry loads are inclined planes. Wedge: Axe, knife and needle are a few examples of a wedge. Inclined planes Wedges staircase ramp knife axe Screw: We use so many screws in wooden furniture. The bottle caps are also a type of screw. Pulley: The rope and wheel used to draw water from a well and a crane used to lift heavy objects are a few examples of a pulley. Screws Pulleys bottle cap screws used pulley used pulley used in crane in furniture to draw water Wheel and axle Wheel and axle: Door knobs and steering wheels of the cars are a few examples of wheel and axle. door knob steering wheel 80
Lever: We use scissors to Levers cut so many things in our bottle opener house. How do you open a cold scissors stapler drink bottle? When we use a bottle opener, it takes less effort to open. The stapler we use to staple papers is a lever. Be Amazed Bicycle is a complex machine that uses simple machines like two wheels and an axle. I Explore (H.O.T.S.) bones and muscles act like levers Do you know our body parts also work as simple machines? Let us find out how. • Our teeth help us to cut with the edge; they act like a wedge. • Our knee and shoulder joints act like wheel and axle. • Our bones and muscles act like levers. The joints where the bones meet becomes the fulcrum. Muscles provide with the effort. A load is anything that we lift, push or pull. Mark the effort, fulcrum and load in the given picture. Connect the Dots Maths Fun A man lifts a 12 kg weight using his hands. He can lift 20 times more using a simple machine. How much can he lift using the simple machine? Simple Machines 81
Social Studies Fun Axes, which human beings have used since ancient times, are a type of simple machine. Probably, it was the oldest tool made out of stone by human beings. A Note to Parent Help your child to list down eight tools used in day-to-day life at home and also categorise them into the six simple machine types. Also, explain to them how simple machines help us in our work. S. No. Machine Types of simple machine Uses at home or office 1 hammer 2 lever used to put nails in the walls or wood 3 4 5 6 7 8 82
Inside the Lab – C Make sure you do these activities only with the help of a teacher or an adult. Activity C1: Simple Machine We have learnt that simple machines help us to do different types of work easily. Let us make a simple machine using some pencils. Let us also find out how they make the work easy. You will need: one brick per group, 10 pencils per group You need to: 1) divide the class into groups of four. 2) ask a student from each group to push a brick across the floor or a stone slab. Is it an easy task? 3) ask each group to take 10 pencils. How could you move the brick more easily using the pencils? Take group members’ suggestions. 4) put the pencils under the brick and roll it across the pencils. Was it easier this time? 5) move other things such as books in the same manner. See if there is a difference. Find out how people in the olden times may have used this simple machine to move big objects. Activity C2: Catapult A catapult is a simple machine used to throw stones or any object. Let us make a simple catapult using some easily available materials. Let us also find out how they help us to throw stones easily. You will need: nine craft sticks or ice cream sticks, six good quality rubber bands, one plastic spoon 83
You need to: 1) take seven craft sticks, and tie one rubber band each tightly around two ends to bound them all together. 2) take two sticks, and tie a rubber band on one of the ends. Try to tie the rubber band close to the edge of the sticks. 3) insert the stack of seven sticks through the two stick bundle. 4) tie these two pieces with a rubber band in a cross fashion as shown in the given image. 5) use few rubber bands, and attach the plastic spoon at the open end of the two sticks. 6) try catapulting pebbles or other small objects. 84
Search
