202110326-MAGNOLIA-STUDENT-TEXTBOOK-EVS_I(SCIENCE)-G05-PART2

EVS – I (SCIENCE) TEXTBOOK – PART 2 5 Name: ___________________________________ Section: ________________ Roll No.: _________ School: __________________________________

Preface IMAX partners with schools, supporting them with learning materials and processes that are all crafted to work together as an interconnected system to drive learning. IMAX Program presents the latest version of the Magnolia series – updated and revised after considering the perceptive feedback and comments shared by our experienced reviewers and users. The Magnolia series endeavours to be faithful to the spirit of the prescribed board curriculum. Furthermore, to facilitate comprehensive coverage, improved understanding of diverse themes and ease of implementation, the EVS curriculum has been split into EVS – I (Science) and EVS – II (Social Studies). Our books are split into two parts to manage the bag weight. They also strive to ensure inclusiveness in terms of gender and diversity in representation, catering to the heterogeneous Indian classroom. The Magnolia EVS – I (Science) textbooks and workbooks offer the following features:  Interactive content that engages students through a range of open- ended questions that build curiosity and initiate exploration  Opportunities for experimentation, analysis and synthesis of ideas and concepts  Exposure to locally relevant environmental problem solving  Effective use of visual elements to enable learning of structures, processes and phenomena  A focus on subject-specific vocabulary building  Integrated learning of values and life skills  Promotion of participatory and contextualised learning through the engagement of all relevant stakeholders in the learning process Overall, the IMAX Magnolia EVS – I (Science) textbooks, workbooks and teacher companion books aim to inculcate healthy habits, skills and values that promote environmentally sensitive and culturally responsive democratic citizenship among students. – The Authors

Textbook Features Let Us Learn About Think Contains the list of learning objectives to Introduces the concept/subtopic and be achieved in the lesson arouses curiosity among students Understanding Remembering Explains the aspects in detail that form Introduces new concepts to build on the basis of the concept the prerequisite knowledge/skills required Includes elements to ensure that students to understand and apply the objective are engaged throughout of the topic Application Amazing Facts Connects the concept to real-life Fascinating facts and trivia related to situations by enabling students to apply the concept what has been learnt through the practice questions Higher Order Thinking Skills (H.O.T.S.) Encourages students to extend the concept learnt to advanced application scenarios Inside the Lab Provides for hands-on experience with creating, designing and implementing something innovative and useful

Contents 5Class 7 Food for Animals����������������������������������������������������������������������������������������������������������� 1 8 Food Production����������������������������������������������������������������������������������������������������������� 5 9 Forests as Shelter�������������������������������������������������������������������������������������������������������� 10 Inside the Lab – B�������������������������������������������������������������������������������������������������������������� 14 Activity B1: Seed Germination Activity B2: Food Web 1 0 Space Travel��������������������������������������������������������������������������������������������������������������� 17 1 1 Wildfire������������������������������������������������������������������������������������������������������������������������ 21 1 2 Cyclones and Floods������������������������������������������������������������������������������������������������� 24 1 3 Earthquakes and Tsunami����������������������������������������������������������������������������������������� 27 1 4 Simple Machines�������������������������������������������������������������������������������������������������������� 31 Inside the Lab – C������������������������������������������������������������������������������������������������������������� 35 Activity C1: Simple Machine Activity C2: Catapult

Lesson Food for Animals 7 Let Us Learn About r herbivores, carnivores and omnivores. u body adaptations of animals to suit their eating habits. a food chain and food web. h how some animals may disappear from the Earth. Think Saleena was eating lunch. She found a squirrel on a tree near the window. She wondered where it got its food from. Do you know how animals find food? Remembering Animals cannot make their food. So, they eat plant parts or other animals that they find in their surroundings. For example, a squirrel finds its food a squirrel eating termites from the surroundings. It collects fruits and nuts from different plants. It may eat some insects too. Have you seen a squirrel collecting groundnuts squirrels eating termites? 1

What does a cow eat? Does it eat termites like the squirrel? No. It eats grass, fruits or vegetables. Animals around us differ in their eating habits. They are of three types based on their eating habits. 1) Herbivores (‘herb’ means ‘a plant’, and ‘vore’ means ‘eat’): These are animals which eat only plant parts as their food. Cows, rabbits, deer are a few examples of herbivores. a cow eating grass 2) Carnivores (‘carni’ means ‘flesh’, and ‘vore’ means ‘eat’): These animals eat other animals as their food. For example, the lion, tiger, leopard and so on. 3) Omnivores (‘omni’ means ‘all’, and ‘vore’ means ‘eat’): These animals eat both plants and animals as their food. For example, human, bear, crow, squirrel and so on. herbivores carnivores omnivores Understanding Now, let us learn how animals find food themselves ants have a sharp from their surroundings. sense of smell If we happened to spill some sugar on the floor, within minutes, it would be surrounded by ants. How do they find it? They can smell it. If we sit outside the house or school to have some food, a crow may fly down and take away our food. 2

Birds can see things from far away. So, they notice the food on our plate even when they fly high in the sky, or sit on a tree far away from us. Animals find their food with the help of their senses. Their eagles spot their prey senses are far stronger than ours. Can we smell the sugar kept from far away in a container inside the cupboard? No. But, ants can. This strong sense of smell helps them to find their food. In the same way, birds can find food with the help of their sharp eyes. Have you seen a cat waving its ear, when we make a scratching sound on the table or ground? They have a sharp sense of hearing. This helps them to find their prey. Do you remember reading about birds and beaks and that the cats have a sharp sense shapes of beaks are suitable for the food they eat? Similarly, have of hearing you ever observed the teeth of a cow? Are they different from that of a dog? Cows have flat teeth. But dogs and cats have sharp, pointed teeth. Why are they different? It is because the food they eat is different. a dog has sharp teeth Cows eat grass. They need flat teeth to grind the plant parts. Dogs and cats eat flesh. They need sharp teeth to tear the flesh. A rabbit has strong front teeth. These help the rabbit to bite food like carrots easily. Some animals use their tongue to sense the prey as well as to catch them. For example, frogs and lizards. Snakes have many senses that help them to find their food. They strong front teeth sense the movement and smell of their prey. help a rabbit to bite a frog uses its tongue to catch the prey a snake uses its sense of smell and movement Application What does an eagle eat? It eats small animals like rats. What do the rats eat? They eat fruits and seeds of plants. From where do these plants get their food? They make their food using sunlight, carbon dioxide, water and nutrients. Food for Animals 3

In this way, plants and animals are linked to each other by eating and being eaten. This is called a food chain. a food chain food web Food chains are also connected to each other. For example, plants can be eaten by a deer or a rabbit. The deer can be eaten by not only a lion but also a tiger. The plants can be eaten by a mouse. The mouse can be eaten by a large bird. Such connected food chains form a food web. Amazing Facts The largest carnivore on Earth is the South Atlantic elephant seal. It usually weighs 3,500 kg. South Atlantic elephant seal Higher Order Thinking Skills (H.O.T.S.) All animals need food to live. What will happen if they do not get enough food from the surroundings? Some of them may die. Their number will decrease in that area. If the food in the surroundings became more scarce, their number will decrease further. In this way, some animals may disappear from the surface of the Earth. Many animals have disappeared from the Earth in this way. Some animals are in danger now. Only a few of their kind are left. The Asiatic lion, Bengal tiger, red panda, snow leopard are few animals whose number has decreased. Asiatic lion Bengal tiger red panda snow leopard 4

Lesson Food Production 8 Let Us Learn About R farms. U how farmers grow food plants. A the journey of food from the farms to our homes. H growing plants without harming the environment. Think Arvind enjoys eating mangoes, and his favourite vegetable is spinach. What are your favourite fruits and vegetables? Have you ever thought about where these food items come from and how they reach your house? Remembering We buy fruits, vegetables, grains, pulses and so on from the market. We also buy milk, meat and fish. We know that all these food items come either from plants or animals. Where are all these plants and animals grown? Who takes care of them? Let us find out. In villages, you must have seen open fields where some plants are grown. You may have seen some people working in those fields. There may have also been some animals like goats, 5

cows, buffaloes and so on. These are farms. A farm is a piece of land used to grow crops and raise animals. People grow different types of useful plants on farms. In some farms, animals that give eggs, milk and meat are also grown. Growing useful plants and raising livestock on a farm is called farming. The people who do these activities are called farmers. farming What are the different types of plants and animals farmers grow on their farms? They grow plants which give us food like vegetables, fruits, cereals, pulses, oilseeds and spices. They also grow sugar cane, tea plant, coffee plant, rubber tree and so on. The animals which are reared on farms include birds like chickens and ducks, cows, buffaloes, goats, pigs and so on. Some farmers rear fish, prawns and so on. Understanding How does a farmer grow plants on his or her farm? Let us find out. 1 First, the farmer has to decide which crops to grow. You know that plants grow from the seeds. So, to grow plants, the farmer needs seeds of these plants. He or she may use the seeds already stored or may buy them from some other people. 2 We have learnt that seed germination needs air, water, sunlight and nutrients from the soil. Once the seeds are ready, the farmer prepares the land to sow these seeds. The soil is cut, lifted, turned over and crushed. This is done to make sure that the soil becomes loose and airy. This help the seeds to get more air and sunlight to germinate. A plough is used to prepare the soil. preparing the soil using animals and machines Farmer may use the plough with the help of animals such as oxen and buffaloes. They may also use machines such as a tractor for this purpose. 3 Plants need nutrients from the soil to grow. So, some nutrient-rich materials are mixed with the soil. 6

4 Then, the seeds are put in the soil and sowing covered with a loose layer of soil. This is sowing. 5 After sowing, the field is watered to help the seeds to germinate. In a few days, small plantlets growing plantlets will grow from the seeds. from seeds 6 They water the plants regularly with the help of water channels made in the fields. They may use sprinklers too. To grow some plants, the entire field needs to be flooded with water. field flooded field watered water channels with water using sprinklers in a farm 7 Farmers remove grass or any other unwanted plants which may grow in the field. 8 Once the plants reach a certain stage of growth, some more nutrient-rich materials may be added to the soil to help the plants grow. 9 Fully grown plants give rise to flowers and fruits. Then, the useful parts of the plants are collected from them. This is called harvesting. In some plants, the fruits are harvested. In other plants, parts such as the stem, leaves, flowers or seeds are harvested. Harvesting is done by people or with the help of machines. While harvesting, some unwanted plant parts may also come along. These are removed, and the required parts of the plant are cleaned up to be used as food. harvesting Food Production 7

Application The food harvested from farms needs to be stored in a safe place. Otherwise, they will get spoilt. From the farms, they are carried to their storage places. These storage places are called godowns. These godowns are kept dry and airy. godowns They are also kept free from insects and animals like rats that eat the food items. From these godowns, food is transported to the main markets. From the main market, this reaches the local markets. We buy this food from the local market for our use. Amazing Facts Some of the first food plants to be wheat grown by humans were wheat and barley. Although the method used to grow them has changed, we still grow the same plants as we did around 10,000 years ago! barley Higher Order Thinking Skills (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 8

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. Food Production 9

Lesson Forests as Shelter 9 Let Us 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. 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? Remembering 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 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. 10

Forests which get rain throughout the year evergreen rainforest forest which changes remain green always. We call them evergreen colour 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. Understanding 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 beetle no proper road to walk. The guide in front of us guided us through a monkeys on a tree narrow way between the bushes. When I looked up, I could not see the sky properly. The branches branches of trees were spread forming a cover overhead. covering the sky 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. Suddenly I heard a rustling sound from the ground. I berries beehive 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. There were huge termite mounds here and there. crawling snake forest soil 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 ground covered termite mound only in moist places. Along with them, there were some with leaves plants with palm tree like leaves. Forests as Shelter 11

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 twiners with thick poisonous fruits colourful fruits. The guide told us that some of them were stems 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. elephants near the forest stream 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 bats on the tree kingfisher woodpecker on a other side of the stream, a woodpecker catching a fish tree was pecking on the dried up branch of a tall tree. Far ahead of us, I found some shelters. I wondered, who lived 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.” Application 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? 12

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 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. 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. Amazing Facts Some forests are found near the seashores. They are Sundarbans 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. Higher Order Thinking Skills (H.O.T.S.) Look at the aerial view of the Amazon rainforest. It the Amazon rainforest, Brazil appears like looks like a green carpet, doesn’t it? Forests form a a green carpet 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 forest cover is reduced, the carbon dioxide 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. Forests as Shelter 13

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 14

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: • The 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 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 Inside the Lab – B 15

• 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. 16

Lesson Space Travel 10 Let Us 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. 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? Remembering 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. 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. 17

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 rocket spacecraft aircrafts out of Earth’s gravity pull. If a rocket steers through the atmosphere carrying an aircraft, 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 can either carry human beings or an artificial satellite. Understanding 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? Astronauts Rakesh Sharma Sunita Williams Kalpana Chawla Look at the pictures of the astronauts. They wear special suits. Do you 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 spacesuit the International Space Station (ISS) 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. 18

Application 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. space food 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 eating in space punches. 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 spacewalk experiments carried out and research in space. For example, the in space 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. Why do astronauts travel to space and other heavenly sleeping in space 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 view of the Earth space and aliens as travel to other heavenly bodies to find whether there is life on them. Have you watched any movies that from space shown in movies show space travel and the living things which live on other planets (aliens)? Space Travel 19

Amazing Facts 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 Higher Order Thinking Skills (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 to orbit the Earth in a spacecraft, walk in space or visit Mars! 20

Lesson Wildfire 11 Let Us Learn About R natural disasters – wildfires. u the causes of wildfires. a the effects of wildfires. h avoiding human-made wildfires. 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? Remembering 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. All these can kill humans, animals and plants and can destroy houses, roads and so on. They are disasters caused by nature. 21

Let us learn about one of the natural disasters – wildfires. We will learn about some other natural disasters in the upcoming lessons. Wildfires are the fires which break out in the forests, grasslands and so on. In India, wildfires are very frequent. Around 20,000 wildfires wildfire occur in India every year. In the state of Uttarakhand, around 1600 wildfires broke out in 2016. Wildfires are common across the world. Understanding 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 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 fire triangle 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 fire may spread from a fields burning cigarette stick Application If a forest catches fire, along with all the forest products, wildlife will also be destroyed. 22

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 controlling wildfire or grassland close to where we live, we have to vacate our houses. We have to move to safer places till the fire settles down. Amazing Facts Wildfires occur on every continent except Antarctica as there are no forests in Antarctica! Higher Order Thinking Skills (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. Wildfire 23

Lesson Cyclones and Floods 12 Let Us Learn About R cyclones. u how cyclones may cause floods. a support given to cyclone-affected people. H preparing in advance for cyclones. 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? Remembering 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. 24

A cyclone may look like this. It has a calm centre called the eye. Around the eye, winds blow at a high speed. Cyclones are formed over the ocean. They move towards the land. They bring heavy rains along with them. Understanding When cyclones hit land areas, the powerful winds destroy 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 a tree uprooted by a cyclone view of a flooded area in is a sudden rise in the water in Andhra Pradesh Odisha after a cyclone level making land areas submerge in water. Application 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 temporary shelters rescue camps or shelters for the affected people. At the rescue camps, these cyclone-affected people are provided with food, water and clothes. Flood water may take days to drain off. 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. Cyclones and Floods 25

Amazing Facts 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. Higher Order Thinking Skills (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. 26

Lesson Earthquakes and Tsunami 13 Let Us 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. 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? Remembering seismograph Sometimes the ground shakes. It may move up and down 27 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. A device called the seismograph is used to measure the 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. the Pacific Ring of Fire Understanding 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? broken upper layers Their edges may bend, or one of them may slide over the other. All of the Earth 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. Now, ask another person to give a light bang on the lower part of the tray. Observe what happens to the water. Bang a little harder. Observe the changes in the water. What do you find? 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’. tsunami moving towards the shore 28

Application 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. tsunami waves wash off buildings and vehicles 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. 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. Amazing Facts 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! Earthquakes and Tsunami 29

Higher Order Thinking Skills (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. 30

Lesson Simple Machines 14 Let Us 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. Think Have you ever played on a see-saw with your friend? How can it lift you up and bring you down? Remembering 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 carpenter putting a nail in the wall? What do they use? Why do they need a hammer? using a slope to unload using a hammer to put in a nail 31

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 to put the wooden planks together while making drawing water from a well joining wooden furniture? using a wheel and rope planks together 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: simple machines inclined plane, wedge, pulley, screw, lever, wheel and axle Understanding Let us now understand how these simple machines work and make things easier. 1) Inclined plane: slope 2) Wedge: inclined plane A sloping or A wedge is a simple machine. It is used to slanting surface separate any two objects by pushing them makes an away from each other. inclined plane. The slant of the A wedge is also like an inclined plane. It inclined plane has a slanting edge which is sharp. It can can move an be used to lift things. Most of the times, it object from one helps us in cutting something. Example: an level to another. axe is used to cut wood 3) Screw: wedge cutting wood using a wedge A screw is a type of inclined plane. In (axe) a screw, an inclined plane is twisted (swirled) around a rod such as a road screw twisted roads around the hill. Screws are useful for holding things together tightly. Example: A screw is used to connect two wooden or metal blocks together. 32

4) Pulley: 5) Wheel and axle: axle wheel A pulley is a pulley Wheel and axle wheel and axle wheel with a make work easier by rope around it. crane using reducing friction. A Pulleys make lifting the pulley wheel helps things objects easier. For to move. The axle example, cranes helps the wheel turn. bicycle wheel use pulleys to lift Example: wheels of with axle heavy vehicles and a bicycle and other building materials. vehicles 6) Lever: fulcrum Lever is a bar, rod or a lever kids playing on a see-saw 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 Application 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. Simple Machines 33

Screws Pulleys bottle cap screws used pulley used pulley used in crane in furniture to draw water Wheel and axle: Door knobs and steering wheels of the cars are a few examples of wheel and axle. Lever: We use scissors to cut so many things in our house. How do you open a cold drink bottle? When we use a bottle opener, it takes less effort to open. The stapler we use to staple papers is a lever. Wheel and axle Levers door knob steering wheel scissors bottle opener stapler Amazing Facts Bicycle is a complex machine that uses simple machines like two wheels and an axle. Higher Order Thinking Skills (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. 34

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 35

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. 36