Textbook ISBN 978-981-14-2828-9 First Published 2020 PRIMARY 2 6001 Beach Road, #14-01, Golden Mile Tower, Singapore 199589. E-mail: [email protected] Printed in Malaysia by The Commercial Press Sdn. Bhd. Lot 8, Jalan P10/10, Kawasan Perusahaan Bangi, Bandar Baru Bangi, 43650 Bangi, Selangor Darul Ehsan, Malaysia. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, photocopying, mechanical, recording or otherwise, without the prior permission of Praxis Publishing Singapore Pte. Ltd. © Praxis Publishing Singapore Pte. Ltd. 2020 The URLs in this book were reviewed and deemed suitable at the time of publication. This cover has been designed using resources from Freepik.com, image by BlueRingMedia. Consulting author Giam Kah How
Contents LIVING THINGS AND LIFE PROCESSES Chapter 1 Our Needs 1 1.1 Food 2 1.2 Exercise 8 1.3 Resting and Sleeping 9 1.4 Water 10 1.5 Air 11 1.6 Clothes 12 1.7 Shelter and a Healthy Environment 12 Chapter 2 Basic Needs and Protection of Animals 17 2.1 Basic Needs of Animals 18 2.2 Protection of Animals 25 2.3 Useful and Harmful Animals 28 2.4 Caring for Animals 32 Chapter 3 Basic Needs and Protection of Plants 35 3.1 Basic Needs of Plants 36 3.2 Protection of Plants 42 3.3 Useful and Harmful Plants 45 3.4 Caring for Plants 48 ENERGY AND THEIR CHANGE Chapter 4 Light and Shadows 51 4.1 Sources of Light 52 ii
4.2 Shadows 53 MATTER AND THEIR PROPERTIES Chapter 5 Mixtures 58 5.1 Ways to Separate Mixtures 59 5.2 Soluble and Insoluble Materials 64 5.3 Ways to Dissolve Materials Faster 66 EARTH AND THE UNIVERSE Chapter 6 Water 71 6.1 Sources of Water and Its Uses 72 6.2 Properties of Water 76 6.3 Water Quality 81 6.4 Conservation of Water 83 Chapter 7 Air 87 7.1 Components of Air 88 7.2 Importance of Air 90 7.3 Movement of Air 92 Chapter 8 Rotation of Earth 97 8.1 Day and Night 98 8.2 Directions 105 STEM Activity 111 iii
Special Features Let’s Think Let’s Try! Let’s Scan What pupils already know Reflects what pupils have learned Challenges pupils with questions that promote higher-order thinking skills What pupils would like to explore as they study the chapter Helps pupils to master their scientific knowledge and skills Provides direct access to the relevant information on the Internet by scanning the QR codes given A diagram to ‘map’ out all the concepts in the chapter An activity that engages in applying the knowledge of scientists, mathematicians and engineers Explain It Map It Out Provides direct access to extra questions by scanning the QR codes given Explains difficult terms used in the text Encourages pupils to find information and present their findings Let’s Find Out! STEM Activity Online QuickQuiz Special Features Presents extra information that is relevant to the concept learned Let’s Know More iv
Our Needs Mother always asks us to eat fruits and vegetables. She also asks us to drink milk. Do you know why? What do I know about our needs? 1. 2. 3. What do I want to know about our needs? 1. Classify food into groups. 2. Explain the needs of exercise, having enough rest and sleeping. 3. State the functions of water in the human body. 4. Explain the importance of air in breathing. 5. State the importance of clothes, shelter and a healthy environment as human needs. Chapter 1
1.1 Food Let’s Try! What did you have for lunch? 1. List the food you eat for lunch over five days. My lunch Day 1: Day 2: Day 3: Day 4: Day 5: 2. Did you have the same food for lunch every day? 3. Over the past five days, (a) what did you eat the most? (b) what did you eat the least? (c) which food do you like the most? Why? (d) what is your conclusion about your lunch? 2 Hands-on Science Primary 2
Egg We eat a variety of foods every day. Food gives us energy, helps us grow and stay healthy. Fish, meat, eggs, milk and chicken help us grow. Rice, noodles, potatoes, bread and cakes give us energy. We need energy to walk, play and study. Rice Noodles Potatoes Bread Cake Fish Meat Milk Chicken Let’s Think Growing children need to drink milk and eat cheese, fish and meat. Why? Chapter 1 Our Needs 3
We eat fresh fruits and vegetables to help us stay healthy. Bananas Cauliflower Tomatoes Papaya Pineapple Growing children like you need all these groups of food every day. What are the foods that you like most in each of these three groups? Broccoli Lettuce Salty snacks, soft drinks and candies are unhealthy food. Eat less. Let’s Think Julie loves junk food. What happens if she eats junk food every day? 4 Hands-on Science Primary 2
Let’s Try! Do you eat the three groups of food? 1. List the food that you ate for lunch yesterday. 2. Group your food into these groups. Food that gives you energy Food that helps you grow Food that helps you stay healthy 3. Did your lunch contain all the three groups of food? 4. If not, what should you do? 5. What is your conclusion from this activity? Chapter 1 Our Needs 5
Each food group contains nutrients that we need. We should eat them in the right amounts as shown below. Tips: • Cut down on foods that are oily, high in sugar or salt. • Drink water or low-fat milk. Carbohydrates give us energy to do work. Quarter plate of your meals Proteins help to repair our body and build strong muscles. Quarter plate of your meals Vegetables and fruits contain vitamins and minerals to keep us healthy. Half plate of your meals 6 Hands-on Science Primary 2
Fried foods are oily and high in fats. Eat them in small amounts. Eating too much of food containing oils and fats can make you overweight. It is important that we exercise often to keep fit. Make a good habit of rinsing your mouth after eating. Brush your teeth twice a day and have regular dental visits. Avoid taking food or drinks that are high in sugar, such as cakes, sweets and soft drinks. Taking too much can cause toothache. Chapter 1 Our Needs 7
1.2 Exercise We exercise when we play games or sports. Why do we need to exercise? • Exercise keeps our mind and heart healthy. • Exercise keeps us from falling sick easily. • Exercise can build strong muscles, joints and bones. Exercise for half an hour a day to keep your body fit. Remember to warm up before exercising and cool down after exercising. This is to prevent sports injuries. 8 Hands-on Science Primary 2
1.3 Resting and Sleeping To get good sleep at night, we must: • Not eat large meals close to bedtime • Relax before going to bed • Sleep without loud noises and bright lights • Sleep eight to nine hours Do you feel tired after playing? We must get some rest when our body is tired. We can rest by taking a nap during the day. At night, we must sleep early. We will feel fresh when we wake up the next morning. If we sleep too little, we are not able to remember well what we have learned during the day. Chapter 1 Our Needs 9
1.4 Water We need to drink at least eight glasses or about two liters of water every day. Up to 70% of our body is water. We need water to stay alive. What are the functions of water in the human body? We need to drink water every day. Maintains body temperature Prevents constipation Moistens our tissues Carries oxygen and carbon dioxide Carries nutrients and waste materials Dissolves nutrients and minerals so that our body can absorb them 10 Hands-on Science Primary 2
1.5 Air We need air to breathe. Air consists of oxygen. We need oxygen to survive. When we breathe out, we remove carbon dioxide from our body. We breathe to survive. Do you know what happens when we breathe? Nose Windpipe Lungs We breathe through our nose or mouth. The air goes through the windpipe. The air enters our lungs. The air is absorbed into our blood. Chapter 1 Our Needs 11
1.6 Clothes 1.7 Shelter and a Healthy Environment A house is our shelter. It protects us from heat, cold and rain. It keeps us safe from harm. The environment that we live in must be healthy. • It is clean. • It has many plants or trees. • It has fresh air and is free of dust. Not littering is one way to keep the environment clean. Find more information from the Internet about ways to keep the environment clean. Then, present your findings in class. Let’s Find Out! We need clothes to cover our body. In hot weather, clothes protect us from sunburn or wind damage. In cold weather, clothes protect us from rain, snow and wind. We must change our clothes every day and wash them properly. 12 Hands-on Science Primary 2
Air Pollution A polluted environment is unhealthy. Types of pollutions are air pollution, water pollution and soil pollution. Polluted air can cause breathing problems, wheezing, coughing and eye irritation. Smoke and fumes from vehicles and factories release harmful gases into the air. Open burning and forest burning can cause haze. Chapter 1 Our Needs 13
Water Pollution Soil Pollution Throwing waste into the drains, rivers and seas can cause water pollution. Polluted water is poisonous. When fish eat the plants in polluted water, the fish are affected. When we eat the fish, the poison enters our body. It will affect our health. Children like to play with the soil on the ground. When unwanted waste materials are dumped on the ground, the soil is usually affected. Soil pollution can cause skin rashes, eye irritation and headaches. 14 Hands-on Science Primary 2
Fill in the blanks. 1. We need , and to stay alive. 2. Potatoes, rice and noodles give us . 3. Meat, fish and milk help us . 4. Fruits and vegetables help us stay . 5. We should eat a of food from each food group every day. 6. Exercise can help us to build strong and release stress. 7. We need to when we feel tired. 8. Water helps to carry and waste materials in our body. 9. Air is needed for . 10. and protect us from heat and cold. food variety nutrients air shelter water grow healthy muscles rest energy breathing clothes Let’s Scan Chapter 1 Our Needs 15
Online QuickQuiz Map It Out Junk food Food that is low in nutritional value and often high in fats and sugar Haze Something like smoke in the air that makes it less clear, so that it is difficult to see well Pollution Damage caused to air, water, etc. by harmful substances or waste Explain It Gives energy Helps to grow Helps to stay healthy Food Exercise Shelter and a healthy environment Water Clothes Our needs Resting and sleeping Air 16 Hands-on Science Primary 2
Basic Needs and Protection of Animals Chickens give us meat and eggs. What should farmers do to make sure the chickens are growing healthily? What do I know about the basic needs and protection of animals? 1. 2. 3. What do I want to know about the basic needs and protection of animals? 1. State the basic needs of animals such as food, water, air and shelter. 2. Describe how animals protect themselves. 3. Identify useful and harmful animals. 4. Describe ways to take care of a pet. Chapter 2
2.1 Basic Needs of Animals Like humans, animals also have basic needs. They need food, water, air and shelter to stay alive and grow well. Food Animals need food for energy and to grow. There are some animals that eat plants only. They are known as herbivores. A bee collects nectar from flowers. A panda eats bamboo. Cows eat grass. A caterpillar eats leaves. 18 Hands-on Science Primary 2
Some animals eat other animals only. They are known as carnivores. Eagles eat rabbits, birds, squirrels, crab and snakes. They also eat fish such as salmon. Lions only eat meat. They eat small animals such as birds and lizards. They also eat large animals like hippopotamus, zebras, giraffes and buffaloes. Most spiders eat insects and even other spiders. They only feed on the insects that were recently killed or live insects that are trapped in the spider web. They eat pests like flies and mosquitoes. Basic Needs and Protection of Animals Chapter 2 19
Are bears herbivores, carnivores or omnivores? Most bears are omnivores. It also depends on the kind of food sources available to them. Pandas are herbivores. They eat bamboo. Polar bears are carnivores. They eat fats all the time. Some animals eat both plants and other animals. They are omnivores. Chickens eat insects and worms. They also eat small grains like corn, wheat and barley. Brown bears eat grass, fruits, roots and bulbs of plants. They also hunt small animals. Brown bears that live close to the sea feed on fish, especially salmon. 20 Hands-on Science Primary 2
Water Animals need water. They drink water to: • stay healthy • control body temperature • remove waste from their body How much water do animals need to drink every day? Find out more information about the groups of animals below. • Animals that can fly • Animals that live on land • Animals that live in water 1. Give two examples of animals for each group. 2. List how much water they need every day. 3. Compare your findings with those of your friends. Let’s Find Out! Basic Needs and Protection of Animals Chapter 2 21
Let’s Try! Do animals need air to stay alive? 1. Place one tadpole each into the beakers as shown below. Tap water Beaker A Tadpoles Cool boiled water Beaker B Oil layer 2. Observe the tadpoles the next day to see whether they are alive. 3. Record your observations in the table below. Beaker Type of water Does the water have air? Is the tadpole alive? A Tap water B Cool boiled water 4. What is your conclusion from this activity? Things needed: Beakers Cool boiled water Tadpoles Tap water Oil Air 22 Hands-on Science Primary 2
A giraffe breathes air through its nostrils. Shelter Animals need air to breathe. Land animals get air directly from the atmosphere. Different animals breathe in different ways. Let’s Think Do fish need air in water? How do they get their air supply? Animals need shelter. This is to protect them from danger and bad weather like hot, cold, rainy and stormy weather. There are various types of shelters. Nests Most birds’ nests are made of grass, leaves and twigs. Basic Needs and Protection of Animals Chapter 2 23
Birds like woodpeckers make holes in trees as nests. They hunt for food and feed their babies in the nest. Underground holes or tunnels Earthworms dig tunnels by eating up the soil in front of them. Caves Bats need to sleep during the day. Caves provide protected shelter for them and they sleep by hanging themselves from the ceiling of the cave. 24 Hands-on Science Primary 2
2.2 Protection of Animals Animals need to protect themselves from danger and enemies. They have special characteristics and behaviors to do so. The bodies of snails are covered by a hard shell. The shell protects them from their enemies. Tigers have sharp claws to fight off and injure their enemies. The bodies of tortoises are also covered by a hard shell. They can pull their head and legs inside their shell. Basic Needs and Protection of Animals Chapter 2 25
We produce anti-venom serum from snakes to save people who are bitten by poisonous snakes like cobras. Wasps can weaken or kill their enemies by giving them a painful sting. Chameleons change their skin color to match the color of their surroundings. This helps them hide from their enemies. They can change from green to the color of a tree trunk. Scorpions and wasps defend themselves by using their poison. Scorpions have a curved tail with a poisonous sting to sting their enemies. 26 Hands-on Science Primary 2
Millipedes curl up their body, pretending to be dead when they are attacked by their enemies. Porcupines have a covering of spines on their body. The spines are long, stiff hairs like needles. The spines can injure enemies that go near or attack them. Buffaloes live and move from place to place in groups. When they are in danger, they defend themselves by staying together. Basic Needs and Protection of Animals Chapter 2 27
2.3 Useful and Harmful Animals A working cow A working police dog Some animals are very useful to us. They provide us with food. Do you know which useful animals provide us with food? Some animals help us in our work. Examples of food from animals In some places, cows and buffaloes are used to plough the soil. Some dogs are trained to help police to sniff out drugs and fight crime. Some are trained to guide the blind. 28 Hands-on Science Primary 2
Donkeys and camels are used to transport goods and people. Sheep provide wool for us to make clothes. Skin from snakes and crocodiles is used to make bags, belts and shoes. Insects such as butterflies and bees help plants to reproduce. Donkeys in hilly areas Camels in deserts Sheep Woolen clothes Butterfly Basic Needs and Protection of Animals Chapter 2 29
Some animals are harmful to us. Cockroaches, flies and rats are harmful animals. They are dirty and carry germs. The germs can spoil our food and drinks that are not covered. We get food poisoning if we eat or drink the food. If you have a serious fever, please visit the doctor immediately to get proper treatment. Houseflies collect germs on their legs and mouths when they make contact with garbage or feces. When they land on your food, it takes only a few seconds to transfer the germs onto your food. Some mosquitoes spread sickness like malaria and dengue when they bite us. 30 Hands-on Science Primary 2
If you can hear a hollow sound when wood is tapped, there is a chance your house has termites. Some animals are poisonous. They produce poisons that cause pain and death. Can you name some of these poisonous animals? Termites are wood-eating insects. They destroy everything that is made of wood. A piece of wood can be damaged and eaten by termites. Basic Needs and Protection of Animals Chapter 2 31
2.4 Caring for Animals We keep animals as pets. Pets are our companions. We need to take good care of our pets. Having a pet helps kids learn how to take care of things. We need to provide a proper place for our pets to live. We play with our pets. We need to give proper food and clean water to our pets. We bring them to a veterinarian if they are sick. 32 Hands-on Science Primary 2
Fill in the blanks. 1. Animals need , water, shelter and to live. 2. eat plants only. 3. eat other animals only. 4. eat both plants and other animals. 5. Animals protect themselves from and enemies. 6. A lizard off its tail when it feels threatened by an enemy. 7. Animals provide us with food and materials for . 8. Some animals help to the fields and some help to transport people and . 9. Some animals cause and cause us pain. 10. To take good care of pets, we should give them a to stay, proper food and water, play with them and take them to a when they are sick. omnivores place carnivores plough goods danger herbivores air veterinarian food breaks sickness clothing Let’s Scan Basic Needs and Protection of Animals Chapter 2 33
Online QuickQuiz Map It Out Carnivore An animal that eats other animals only Herbivore An animal that eats plants only Omnivore An animal that eats both plants and other animals Shelter A place for protection from bad weather, danger or attack Veterinarian Animal doctor Explain It Taking care Needs Protection Basic needs and protection of animals Food Water Air Shelter • Sharp claws • Hard shell • Spines • Body shape or color that matches the surroundings • Breaking off a body part Useful and harmful 34 Hands-on Science Primary 2
Chapter 3 Basic Needs and Protection of Plants Farmers grow paddy plants in paddy fields. How do they ensure that the plants grow well? What do I know about the basic needs and protection of plants? 1. 2. 3. What do I want to know about the basic needs and protection of plants? 1. State the basic needs of plants such as water, sunlight, air and nutrients. 2. Describe how plants protect themselves. 3. Identify useful and harmful plants. 4. Describe ways to take care of plants.
3.1 Basic Needs of Plants Let’s Try! Do plants need water? 1. Place two similar potted plants in the sun. 2. Water plant P every day for two weeks. 3. Do not water plant Q. P Q 4. Observe the plants for two weeks. What do you observe after the first week and the second week? P: Q: 5. Which plant is not growing healthily? Explain. 6. Did both plants receive the same amount of sunlight? 7. Did both plants receive the same amount of water? 8. What is your conclusion from this activity? Things needed: Similar potted plants Water 36 Hands-on Science Primary 2
Plants need water to grow. Without water, plants will wilt and die. Suda waters her plant every day. Chet is too lazy to water his plant. Suda’s plant is growing healthily. Chet’s plant is wilting. Basic Needs and Protection of Plants Chapter 3 37
Plants need the right amount of water for healthy growth. However, too much water is bad for plants too. Plants will wilt and die if they do not get enough water. Let’s Think Why do plants die when their roots are in the water for too long? 38 Hands-on Science Primary 2
Let’s Try! Do plants need sunlight? 1. Place two similar potted plants in the sun. 2. Cover plant B with a box. 3. Leave plant A in the sun. 4. Water the plants with the same amount of water every day for two weeks. A B 5. Observe the plants for two weeks. What do you observe after the first week and the second week? A: B: 6. Which plant is not growing healthily? Explain. 7. What is your conclusion from this activity? Things needed: Similar potted plants Box Basic Needs and Protection of Plants Chapter 3 39
Do plants need only water and sunlight? No, plants also need air to survive. Without air, plants will die. Plants need sunlight to make food. Without sunlight for too long, the plants will not grow well and may die. Plants need carbon dioxide to make food. Plants need oxygen for respiration. Greenhouse farming is the planting of plants in transparent structures. The warmth needed for the growing of plants can be controlled. 40 Hands-on Science Primary 2
Plants need nutrients to grow well. They absorb the nutrients from the soil through the roots. Roots absorb water and nutrients from the soil. Fertilizers We can add fertilizers to the soil. Fertilizers contain certain nutrients needed by the plants to grow better. Roots Hydroponics is the method of growing plants in water. The water is added with the nutrients that plants need. Basic Needs and Protection of Plants Chapter 3 41
3.2 Protection of Plants Plants have special ways to protect themselves from being eaten by animals. Roses have sharp thorns on their stems. This prevents the animals from getting close to them and eating them. The cactus has long and sharp spines that can keep humans and animals away. The durian fruit is covered with sharp thorns. This plant part can injure the animals that try to eat it. 42 Hands-on Science Primary 2
Coconut is rich in vitamins and minerals. Its flesh is high in protein. Its oil is considered one of the healthiest oils. It is good for our health. Papaya and jackfruit trees can produce latex in their stems, leaves or fruits. Latex causes itchiness that keeps the animals from eating the fruits. A coconut has thick and hard skin. This makes it difficult for animals to open it. Basic Needs and Protection of Plants Chapter 3 43
Work in groups. Name two other ways how plants protect themselves. • Give an example of a plant for each way of protection named above. • Get pictures of these plants. • Describe how these plants protect themselves. Share your findings with your friends in class. Let’s Find Out! The petai fruit has a bad smell too. Its smell keeps the animals that want to eat it away from the plant. Lantana flowers have a bad smell. This stops us from picking them. Certain types of wild mushrooms produce poison. The animals that eat them can fall sick or die. 44 Hands-on Science Primary 2
Ginger, lemongrass, cinnamon and basil leaves are used as herbs and spices that give special flavor. They add taste to our food. Fruits and vegetables keep our body healthy. They provide us vitamins. 3.3 Useful and Harmful Plants There are many plants around us. Some plants are useful while some are harmful. Do you know the plants that are useful to us? Some plants like ginseng help to improve our energy. Basic Needs and Protection of Plants Chapter 3 45