We should handle simple machines properly to avoid getting hurt. The following are some safety guidelines we should follow when using simple machines. • Do not play with sharp and pointed tools such as hammers, knives, needles and others. • Store sharp tools in safe places such as toolboxes or cabinets so that they can be kept out of reach from young children. • Clean tools and return them to where they belong after use to avoid misplacing or losing them. • Inspect tools to make sure that they are sturdy before using them. First aid is the immediate treatment given to a person if accidents happen due to careless handling of simple machines. It should be given to ease someone’s pain and to prevent further injury. What are the safety measures you should take when using simple machines? Check out the pictures shown in this chapter. Cover your hands, elbows and knees when skating. Precautionary Measures in Using Simple Machines 6.2 96 Hands-on Science Primary 5
Fill in the blanks. Some words can be used more than once. 1. A simple machine is a device used to make work . 2. A has a fulcrum, a load and an effort for lifting or moving heavy things. 3. Levers can be classified into types that serve different purposes. 4. A pulley can change the of the force applied. 5. Gears are used to change the and of rotations. 6. A simple machine of wheel and axle is used to lift loads or to a force. 7. An is used to ease the moving of objects from a lower to a higher position. 8. A can be driven into flat surfaces and is used to fasten things and raise weights. 9. Wedges are used to things and to things in place. 10. We need to practice safe use of simple machines to prevent . hold direction screw easier inclined plane injuries three multiply speed split lever Let’s Scan Chapter 6 Simple Machines 97
Map It Out The point at which the lever is resting Fulcrum It is a wheel with a groove. Pulley It is a rod connected to the center of a wheel that allows it to turn. Axle Online QuickQuiz Explain It Wedge It is a piece of wood, rubber, etc. with a pointed edge at one end and a thick edge at the other, either pushed between parts of an object to separate or secure them. Simple machines Precautionary measures Lever Wedge Pulley Gears Wheel and axle Inclined plane Screw To ensure safety To split objects apart and to hold things in place To fasten or hold things tightly and to raise weights To reduce the force applied to move objects up to a higher spot To magnify the force in moving loads To change the direction and the speed of rotations To lift or lower down objects To lift or move heavy things 98 Hands-on Science Primary 5
Chapter 7 What do I know about water and its changes of state? 1. 2. 3. What do I want to know about water and its changes of state? 1. Recall that water can exist in three interchangeable states of matter. 2. Describe how water changes from one state to another when heated or cooled. 3. Describe the water cycle. 4. Explain the roles of evaporation and condensation in the water cycle. 5. Explain the importance of the water cycle. 6. Explain the importance of water for life processes. 7. Describe the impact of water pollution on Earth’s water resources. Water and Its Changes of State If we leave grape fruit juice with ice on the table, the ice in the glass will become less after a while. After some time, the ice will disappear. Do you know why this happens?
Water can exist in three states of matter, namely solid, liquid and gas. Ice is the solid state of water, water is the liquid state and water vapor is the gaseous state. Water changes from one state to another when it is heated or cooled. When water is heated, it gains heat. The temperature increases. When water is cooled, it loses heat. The temperature decreases. When ice which is the solid state of water gains heat from its surroundings, it changes from a solid to a liquid state (water). This process is called melting. It takes place at the temperature of 0°C which is the melting point of ice. Melting When water in the liquid state loses heat to its surroundings or is cooled to 0°C, it changes from a liquid to a solid state (ice). This process is called freezing. The temperature of 0°C is the freezing point of water. Freezing 7.1 Changes of State in Water Water in the solid state has a definite shape and volume.e Solid state of water Water in the liquid state has a definite volume, but no definite shape. It takes the shape of the container. Liquid state of water 100 Hands-on Science Primary 5
Let’s Think • What are the three examples of water in the solid state? • Water is colorless. What are the two properties of water? • What is the difference between steam and water vapor? • When we dry wet clothes in the sun, where does the water go? Explain how it happens. When water is heated to 100°C, it gains heat and changes from a liquid to a gaseous state (steam). This process is called boiling. It takes place at the boiling point of water which is 100°C. Boiling When steam or water vapor in the gaseous state comes into contact with a cool surface, it loses heat to its surroundings, it changes from a gaseous to a liquid state (water). This process is called condensation. It takes place at any temperature. When steam or water vapor condenses, it forms tiny water droplets. Condensation When water gains heat at any temperature below its boiling point, it changes into water vapor. This process is called evaporation. It occurs all the time at any temperature and only on the surface of the water. Evaporation Water in the gaseous state has no definite shape and volume. Gaseous state of water Water and Its Chapter 7 Changes of State 101
1. Leave ice cubes on a plate at room temperature. What happens after 30 minutes? 2. Pour water into the ice cube tray. Then, put it into the freezer. What happens after six hours? 3. Heat up the water in a beaker. What happens when it boils? 4. After that, place a metal spoon above the boiling water without dipping it in the beaker. What can you observe? 5. Record your observations in the table below. Activity Observation In step 1 In step 2 In step 3 In step 4 6. (a) What is the melting point of ice? (b) What is the freezing point of water? (c) What is the boiling point of water? 7. What is your conclusion from this activity? Let’s Try! What are the effects of heat gain or heat loss on the state of water? Things needed: • Bunsen burner • Tripod stand • Wire gauze • Metal spoon • Ice cubes • Plate • Water • Ice cube tray • Beaker Tripod stand Bunsen burner Water Wire gauze Beaker 102 Hands-on Science Primary 5
Hang wet cloths during windy days? Factors Affecting the Rate of Water Evaporation Water evaporates all the time at any temperature below its boiling point. This occurs only on the surface of the water. Therefore, the exposed surface area of water affects how fast water can evaporate. Do you know that the place and the way we hang wet clothes affect how fast the clothes dry? Based on the pictures below, does evaporation happen faster or slower? Hang wet clothes in a shady area? Hang wet clothes by exposing most of their surface area? Hang wet towels in the sun? Hang wet towels by arranging them closely next to each other? Hang wet clothes on gloomy days? Water and Its Chapter 7 Changes of State 103
These are the factors that affect the rate of water evaporation. Exposed surface area When the exposed surface area is larger, water evaporates faster. This is because more water vapor will be able to escape into the air from a larger exposed surface area compared to a smaller one. Presence of wind Water evaporates faster in the presence of wind. The wind takes away the water vapor around the wet objects which allows more water vapor to escape into the air. Water evaporates faster when the surrounding temperature is high. This is because water absorbs heat from the surroundings to get energy and is released as water vapor into the air more easily. Surrounding temperature Humidity in hot weather Humidity refers to the total amount of water vapor in the air. The amount of water vapor that the air can contain depends on the temperature. The higher the temperature, the greater the amount. Therefore, warm air can contain more water vapor that is released from the water surface. The rate of evaporation increases when humidity is low. 104 Hands-on Science Primary 5
Let’s Try! What are the factors that affect the rate of water evaporation? Things needed: • Containers of different shapes and surface areas • Water • Beaker / Measuring cylinder • Identical containers A The exposed surface area 1. Pour 100 ml of water each into three containers of different shapes and surface areas as below. 2. Place the containers in the sun for three hours. 3. Measure the volume of water in the containers after three hours using a beaker or measuring cylinder. Record your results. B The presence of wind 1. Pour 50 ml of water each into two identical containers, G and H. 2. Place container G in a cupboard and container H under a fan. 3. Measure the volume of water in the containers after three hours. Record your results. C Surrounding temperature 1. Pour 50 ml of water each into two identical containers, I and J. 2. Place container I in a shady area and container J in the sun. 3. Measure the volume of water in the containers after two hours. Record your results. Results Activity A B C Container D E F G H I J Volume of water (ml) Questions 1. Which container has the least amount of water at the end of each activity? Explain why. (a) Activity A: (b) Activity B: (c) Activity C: 100 m of water 100 m of water 100 m of water Container D Container E Container F Water and Its Chapter 7 Changes of State 105
2. How do you relate the factor in each activity to the rate of water evaporation? (a) Activity A: The the exposed surface area, the the rate of water evaporation. (b) Activity B: (c) Activity C: 3. What is your conclusion from this activity? About 97% of the water on Earth is in the oceans. The rest is fresh water that contains very little or no salt. The majority of it is locked up in the ice and in the ground. Therefore, less than 1% of water on Earth is available for use. Where does the water in the lakes and rivers come from? The water on Earth is continuously moving from the land to the sky and back again to the land. This process is known as the water cycle. In the water cycle, water is not created or destroyed but changes its form and location. Why can’t we drink seawater since our body needs both water and salt to function? Sea water tastes bad, is toxic and contains too much salt! Our body only needs a small amount of salt. If we take in too much salt, our body has to work harder to get rid of the excess through our urine. This will cause our body to suffer from a net loss of water and increase our thirst. 7.2 The Water Cycle 106 Hands-on Science Primary 5
1 The Sun provides heat energy to evaporate water from seas, rivers, lakes and ponds through the process of evaporation. 2 When water evaporates, it changes into water vapor. Air that contains a lot of water vapor is humid. When humid air is cooled at the higher parts of the sky, the water vapor condenses into tiny water droplets through the process of condensation. They gather to form clouds. 3 As more water vapor condenses, the tiny water droplets combine to form bigger droplets. When these droplets become too big and heavy, they fall to Earth as rain. 4 The rainwater flows to streams, rivers, lakes and the seas where the cycle repeats itself. Water Cycle Water and Its Chapter 7 Changes of State 107
Importance of the Water Cycle The water cycle replenishes the land with freshwater. Living things depend on freshwater for their survival. Rainwater that flows into rivers, lakes and ponds is the main source of freshwater. Plants use freshwater to carry out photosynthesis in making food and they are a food source for animals and humans. Humans also need freshwater as their water supply. The water cycle also helps purify the water. During evaporation, only water is evaporated leaving behind salt, other sediments and pollutants. It also helps to cool the air. Water is one of the basic needs of all living things and life processes. It is important because we use water in many ways. We use water for transportation. Cargo ships carry containers from ports to send to other places. Farmers use water for agriculture. Plants need water to grow. We use water for enjoyment. We carry out activities in the water. Hairdressers use water at the hair salon to wash and rinse the hair of customers. Firemen use water to put out fires and save lives. 7.3 Importance of Water 108 Hands-on Science Primary 5
Work in groups and list three other uses of water. Then, give two examples to save water for each of the following ways: • Reducing water usage • Reusing water • Water recycling Share your work with your friends in class. Let’s Find Out! We get water easily when we turn on a tap. Tap water has been treated to remove bacteria and other impurities before it comes into our home. In other places, people may get water directly from its source such as rivers, ponds, lakes and wells. The water might contain microorganisms that we cannot see with our naked eyes. Therefore, we must appreciate water and use it carefully. Water is precious because it is a limited natural resource. We can save water through reducing, reusing and recycling water. Water pollution is the contamination of water such as in rivers, lakes and oceans by human activities. Water pollution occurs because harmful pollutants are released into water through: • domestic waste from home, such as garbage, feces and food leftovers • commercial waste from shops, such as excessive detergents and rubbish • industrial waste from factories, such as chemicals and heavy metals • agricultural waste from farms, such as fertilizers and pesticides Factories release toxic waste in the water causing water pollution and dirty smoke is released causing air pollution. Polluted water caused by household waste. 7.4 The Impact of Water Pollution Water and Its Chapter 7 Changes of State 109
Water pollution is very harmful to humans, animals and plants especially aquatic life. The effects of water pollution are varied. It depends on the type of pollutants released into the water and the locations of the occurrence. To minimize water pollution, everyone should be involved. For example, • Throw rubbish into the rubbish bin. • Do not throw medicines, oils and paints down the sink or toilet. Check with your local authorities if there is a medicine or chemical disposal plan for local residents. • Use environmentally safe cleaning liquids at home. • Do not overuse pesticides and fertilizers in the garden. Use organic manure instead. Water pollution can cause the organisms that live in or depend on water to be killed. The presence of harmful pollutants in the polluted water will poison and kill the organisms. This is the reason why we see dead fish, birds, sea gulls and crabs often washed up on beaches. Death of aquatic life Polluted water contains harmful pollutants such as lead which are eaten by different kinds of fish in the water. Human health will be affected after eating this fish. In the long run, humans will get diseases such as hepatitis by eating seafood that has been poisoned. Humans might also be infected with cholera as a result of eating food or drinking water contaminated with bacteria. Harmful effects to humans A dead fish in polluted water. Food poisoning after eating contaminated food. 110 Hands-on Science Primary 5
Fill in the blanks. Some words can be used more than once. 1. Water can change from one state to another when it is or . 2. When ice changes from a solid state to water, this process is called . The point of ice is 0°C. 3. When water changes from a liquid state to ice, this process is called . The point of water is 0°C. 4. When water changes from a liquid state to steam, this process is called . The point of water is 100°C. 5. When water changes to water vapor at any temperature below its boiling point, this process is called . 6. When water vapor changes from a gaseous state to water droplets, this process is called . 7. The factors that affect the rate of water evaporation are exposed surface area, presence of wind, and . 8. The processes of and play an important role in the water cycle. 9. The water cycle is important to replenish the land with for the survival of living things. 10. The water is important to all living things and processes. 11. Water pollution occurs because of harmful being released into the water by human activities. Everyone must get involved to help water pollution. 12. Water pollution can cause the of aquatic life and have harmful effects on human . boiling health temperature heated evaporation freshwater minimize pollutants humidity death freezing cooled melting life condensation Let’s Scan Water and Its Chapter 7 Changes of State 111
Map It Out Water and its changes of state Water cycle Importance of water The impact of water pollution Changes of state in water A substance that pollutes something, especially air or water Pollutant The temperature at which a liquid becomes a solid when cooled Freezing point The temperature at which a solid melts when it gains heat Melting point The temperature at which a liquid becomes a gas when it gains heat Boiling point Online QuickQuiz Explain It The way that water is evaporated from the seas, rivers, lakes, etc. and goes back again to the land as rain Water cycle • Melting • Freezing • Boiling • Evaporation • Condensation Evaporation and condensation play an important role in replenishing the land with freshwater. • For enjoyment • Agriculture • Transportation • To use at work • Death of aquatic life • Harmful effects on humans Factors that affect the rate of water evaporation • Exposed surface area • Presence of wind • Surrounding temperature • Humidity in hot weather 112 Hands-on Science Primary 5
Chapter 8 What do I know about the changes in the environment? 1. 2. 3. What do I want to know about the changes in the environment? 1. Describe the process of soil formation and its types. 2. Identify different types of rocks. 3. Describe Earth’s structure. 4. Identify natural disasters and their effects on living things and the environment. 5. Identify human activities that change the environment. Changes in the Environment The top layer of our Earth is covered with soil. What is soil made up of and how does it form? What are the natural phenomena and human activities that happen on Earth affecting the environment?
Soil is made up of air, water, decayed plants and animals, and tiny pieces of broken rocks, such as sand, silt and clay. Soil Formation Plants and animals live, die and decay, then combine with tiny pieces of rocks to form soil. The formation of soil is a slow process as the rock on Earth’s surface is broken down slowly into tiny pieces through a process called weathering. Chemical Weathering Physical Weathering The waves and winds along the coast can wear out the rocks over a period of time. They may carry solid particles such as sand that hits against the big rocks which can lead to the breaking down of the rocks. Chemical weathering involves chemical reactions. Rain dissolves carbon dioxide and other acidic gases in the air to form weak acids. These acids attack rocks such as limestone and marble. Over thousands of years, unique limestone rocks are formed. Limestone rocks are formed at the beach. 8.1 Soil The physical weathering of rocks is due to rain, wind and temperature changes, especially when there is a big difference between the day and night temperature. During the day, the outer layer of a rock is hot while the inner layer is cold. This causes the outer layer to expand slightly. At night, the temperature drops. The outer layer contracts slightly. After some time, the outer layer of the rock cracks and peels off. In some areas, the temperature drops to a very low level. When the water in the cracks of rocks freezes, it expands and widens the crack. After some time, the rocks break into small pieces. 114 Hands-on Science Primary 5
Biological Weathering The biological weathering of rocks is a result of the action by living organisms. For example, some plant roots grow within the face of a rock. When the roots penetrate into the soil in search of nutrients and water, they go through the cracks in the rocks. As they grow, they progressively crack the rock apart. Organisms such as algae, moss and lichens release chemicals that are capable of breaking down the outer layer of rocks. Small animals such as burrowing animals make tunnels in the ground and live inside. This also loosens the rocks. Tree roots growing through rocks. Weathering is different from erosion. Weathering is the process where rock is broken down into smaller pieces. However, erosion happens when rocks and sediments are picked up and moved to another place by water, wind or ice. Weathering and erosion may occur together. There are three main types of soil, namely sandy soil, loam and clay. We can classify soils according to their color, texture and ability to retain water. The texture of a type of soil depends on the proportions of sand, silt and clay present in it. Sandy soil is coarse as it contains a lot of sand. It has large pores that allow water to flow through it easily. Therefore, it is loose, has a lot of air spaces and is unable to retain much water. Coconut palms grow well in sandy soil. Sandy Soil Types of Soil Changes in the Chapter 8 Environment 115
Loam contains organic materials such as decayed leaves and plants. It is finer than sandy soil but coarser than clay. It contains an equal amount of sand and clay. It allows water to flow through it but not too quickly. As a result, it can retain some water and has enough air for roots. Most plants grow well in this type of soil. Lettuce grows well in loamy soil. Loamy soil has moderate-sized pores. Clay is very fine as it contains mainly clay particles. It has very small pores that do not allow water to flow through it easily. As a result, it can retain a lot of water but has very little air. Therefore, clay is soft but sticky when wet. Mangrove trees grow well in this soil. Let’s Think Among sandy soil, loam and clay, which is the richest in nutrients for plant growth? Why? Loam Clay 116 Hands-on Science Primary 5
Let’s Try! What are the properties of soil? 1. Observe the color of the three soil samples and feel them with your bare hands. 2. Observe the texture of the soil samples using a magnifying glass. Record all your observations in the table below. Sample Color of the soil Gritty, smooth or sticky? Texture of the soil Amount of water after one minute A B C 3. What can you infer from these observations? Which sample is sandy soil, loam and clay? 4. Predict the soil sample that can retain more water than the others. 5. To confirm your prediction, investigate the water retention for each type of soil. (a) Fold a piece of filter paper into a cone shape and place it within the filter funnel. (b) Place a handful of sample A into the filter funnel. Place a measuring cylinder under the funnel. (c) Prepare another two sets with samples B and C. (d) Measure 60 ml of water using another measuring cylinder. Prepare three sets. (e) Pour the water into the three funnels at the same time. (f) Record in the same table, the amount of water that is in the measuring cylinder after one minute. 6. Which type of soil allows water to flow through it easily? Which type of soil can retain the most water? Explain. 7. What is your conclusion from this activity? • Three soil samples • Filter paper • Water • Filter funnels • Magnifying glass • Measuring cylinders Things needed: Water Filter paper Filter funnel Measuring cylinder Sample A Water Filter paper Filter funnel Measuring cylinder Sample B Water Filter paper Filter funnel Measuring cylinder Sample C Changes in the Chapter 8 Environment 117
There are many types of rocks. Rocks can be divided into three main groups, based on the way they are formed. They are igneous, sedimentary and metamorphic rocks. Igneous rocks are formed when magma cools and solidifies. Magma is the molten rock found extremely deep in the Earth. There are two types—intrusive igneous rocks and extrusive igneous rocks. The properties of igneous rocks depend on how fast the magma cooled. Igneous Rocks Magma can flow upward due to the great pressure beneath through cracks in the ground. As it rises, it cools slowly and solidifies into igneous rocks with large crystals called intrusive igneous rocks. They are formed from magma that cools and solidifies within the Earth. Intrusive Igneous Rocks When volcanoes erupt, the magma flows to the surface of Earth and is called lava. Lava loses heat to the atmosphere and solidifies very quickly, forming igneous rocks with small crystals called extrusive igneous rocks. Extrusive Igneous Rocks Magma Basalt is a volcanic rock that is used for construction projects. Crushed basalt is used for the road base. Melting Metamorphism 8.2 Rocks Lava Weathering Transport Deposition Granite is a very hard grey or black rock that is used for building. 118 Hands-on Science Primary 5
In groups, make a comparison table to differentiate among igneous rocks, sedimentary rocks and metamorphic rocks. Include the following in your table: • How they are formed • Three examples of rock for each group (include their names and photos) • The characteristics of each example given Let’s Find Out! Weathering agents erode and transport igneous rocks to the seabed, where they are compressed and merged with other materials to form sedimentary rocks. Rocks are constantly being broken down by wind, water and heat into tiny bits and pieces. These tiny bits are called sediments which are washed into rivers and seas, and settle as layers on the riverbed and seabed. Often, minerals and dead living things are also found in the sediments. Over millions of years, layers after layers of sediments are deposited and compressed. Slowly, these layers of sediments lose water, harden and become sedimentary rocks. Sedimentary rocks usually have a layered appearance. They may contain fossils of animals and plants that were trapped in the sediments as the rocks were being formed. Sedimentary Rocks Limestone is a hard sedimentary rock. It is used as building materials and in the making of cement. Metamorphic rocks are formed from other rocks that are changed due to very high pressure and heat without melting. This happens when the rocks are in contact with hot magma or when the rocks are under high pressure in areas where mountains are forming. Some rocks are layered while some are not. The rocks that are buried deep in the Earth can melt to form magma. Metamorphic Rocks Marble, often with a pattern of irregular lines, is used as a building material for floors, tables and other things. Changes in the Chapter 8 Environment 119
Earth can be divided into three main layers: • Crust • Mantle • Core Crust • The crust is the outermost and the thinnest layer of Earth. • It is about 5 km to 60 km thick with temperatures below 500°C. • The crust forms the Earth’s surface where living things live. • Most of the crust consists of igneous, sedimentary and metamorphic rocks. Mantle • The mantle is the layer beneath the crust. • It is about 2900 km thick with temperatures between 200°C to 4000°C. • It is where molten rocks and magma are formed due to high temperatures. Core • The core is the innermost layer of the Earth. • It is made up of two parts, the liquid outer core and the solid inner core. • The outer core is about 2200 km thick and the temperatures can reach up to 3000°C. • The inner core is about 1300 km thick and the temperatures can reach up to 5000°C. • It is mainly made up of minerals, such as iron and nickel. 8.3 The Structure of Earth 120 Hands-on Science Primary 5
Natural disasters, such as volcanic eruptions, earthquakes or tsunamis, are the natural events that can cause loss of life, property damage and affect the quality of the environment. These disasters often happen in Indonesia and they change the surface of Earth. Volcanic eruptions A volcano is a mountain with a large hole at its top which allows magma, gases, steam and dust to escape from the Earth’s crust. During a volcanic eruption, a very high temperature and pressure in the mantle forces the magma out through the opening in the Earth’s crust onto the surface of the Earth. The magma that flows out to the Earth’s surface is called lava. It flows down the slope of the volcano and accumulates there. Volcanic eruptions pollute the air with gas and dust that are harmful to lives, and destroy property. An earthquake is the shaking of the Earth’s surface as a result of volcanic activity or a sudden movement within the Earth’s crust. This happens when two large pieces of the Earth’s crust suddenly slip, producing shock waves that shake the Earth’s surface and causing large cracks in the ground. Powerful earthquakes can cause landslides and tsunamis that change the surface of Earth. Violent earthquakes can cause property damage, causing buildings, flyovers and bridges to collapse. The slip of two large pieces of the Earth’s crust causes a crack in the ground. Earthquakes 8.4 Natural Disasters and their Effects Mount Bromo is an active volcano in Java, Indonesia. Changes in the Chapter 8 Environment 121
Tsunamis Tsunamis are powerful ocean waves that travel at a high speed and become larger as they reach the shore. Most tsunamis are caused by earthquakes, volcanic eruptions or landslides under the sea. An earthquake occurs due to a sudden movement within the Earth’s crust. When this happens underwater, big gaps may appear on the ocean floor. When water moves in to fill the gaps, this causes a tsunami to happen. Therefore, many coastal areas have warning systems in place to inform people to leave the area if there is an earthquake that may cause a tsunami to happen. Tsunamis can cause inland flooding, loss of life and property damage. Rainy seasons especially heavy monsoon rains, usually bring plenty of rainfall. Together with human activities and weak water management, they can cause rivers to overflow and result in floods. Floods cause lives to be lost, plants and animals to die, houses to be damaged and infrastructure to be destroyed. Floods also increase the spread of diseases, such as cholera, malaria and typhoid. Floods 122 Hands-on Science Primary 5
Apart from the natural disasters that change the Earth’s surface, some human activities, such as industrialization, urbanization, mining and land reclamation can also change the surface of Earth. Industrialization When industry is introduced on a wide scale in a country, it is called industrialization. We can see many factories and buildings built to produce goods. To build factories and houses, hills and mountains are flattened. Some swampy areas, seashores and riverbeds are turned into new land. Urbanization To create a city, more houses are built. Medical, shopping, sports and other facilities are provided. Roads and bridges are constructed. All these activities can change the Earth’s surface. Human Activities that Change Earth’s Surface 8.5 Sometimes, a tunnel road cuts through a mountain to provide easy access from one place to another. Changes in the Chapter 8 Environment 123
Mining Mining activities change the land surface through the removal of soil, rock and coal. After digging, if there is not enough material to fill the large holes in the ground, the area will usually be left as puddles or lakes with steep slopes. In groups, share your findings of the following in class: (a) List three examples of natural disasters that have happened in your country, including when and where they happened. State the effects of each of these examples. (b) List two human activities that change the surface of Earth. State the effects of these activities. (c) Describe how humans can prevent or minimize the negative impact on the environment from the activities listed in (b). Let’s Find Out! Land reclamation Humans have been making new land from lakes, rivers and oceans to create additional land spaces for residential areas, industry, agriculture or other purposes. One way to do this is by filling up underwater areas with rocks, cement and clay. Land reclamation usually takes place in areas with limited land for development. Natural disasters and human activities pose negative impacts on the environment such as pollution, destruction of habitats and global warming. We should take proper actions to minimize these impacts as a result of the changing of the Earth’s surface. 124 Hands-on Science Primary 5
Fill in the blanks. Some words can be used more than once. 1. Soil is formed through the processes of weathering which are weathering, weathering and biological weathering. 2. soil allows water to flow through it easily, allows water to flow through it but not too quickly, while does not allow water to flow through it easily. 3. can retain water very well while soil is unable to retain much water. 4. Rocks are divided into three groups that are called , sedimentary and metamorphic rocks based on the way they are formed. 5. Intrusive igneous rocks are formed from that cools and solidifies within the Earth. 6. Extrusive igneous rocks are formed when loses heat and solidifies very quickly on the surface of Earth. 7. Weathering agents transport igneous rocks to the seabed, where they are compressed and merged with other materials to form rocks. 8. When igneous or sedimentary rocks undergo changes due to very high pressure and heat, they are transformed into rocks. 9. Earth consists of the where living things live, the where molten rocks are formed and the that is made up of minerals. 10. Most of the consists of igneous, sedimentary and metamorphic rocks. 11. Volcanic eruptions, earthquakes and tsunamis are natural that can cause loss of life, property damage and affect the quality of the environment. 12. We need to take proper actions to minimize negative impacts to the due to human activities that change the Earth’s surface. disasters loam clay core physical magma sandy lava igneous sedimentary mantle chemical crust environment metamorphic Let’s Scan Changes in the Chapter 8 Environment 125
Map It Out Sand or stone that is carried by water or wind and deposited on the surface of the land or the seabed, that slowly forms a layer of rock Sediment An event that can cause death, great harm or serious damage Reclamation Absorb and continue to hold something Retain The effort to make additional land from seas, lakes or rivers suitable for building, industry or other purposes Disaster Online QuickQuiz Weathering The processes by which rock is broken into smaller pieces by the action of the weather such as sun, rain and wind Human activities that change Earth’s surface Changes in the environment Natural disasters and their effects The structure of Earth Soil Rocks Soil formation • Physical weathering • Chemical weathering • Biological weathering Type of soil: • Sandy soil • Loam • Clay Explain It Types of rocks: • Igneous rocks • Sedimentary rocks • Metamorphic rocks • Crust • Mantle • Core • Volcanic eruptions • Earthquakes • Tsunamis • Floods • Industrialization • Urbanization • Mining • Land reclamation 126 Hands-on Science Primary 5
STEM Activity A magic tool Flowers are the reproductive organs of a plant. Pollination is an important part of the life cycle of a flowering plant. Plants usually rely on insects or the wind for pollination but we can help them to pollinate too. Hand-pollination is a technique used when natural or open pollination is insufficient or undesirable. Hand-pollination is a common technique used at home and in small-scale gardens. You are required to design a tool to pollinate bell-shaped flowers. Search for information regarding the pollination of bell-shaped flowers. Choose appropriate materials. Suggested materials: String Scissors Forceps • What is the aim of this activity? • What do you need to know to get started? • What are the aspects that you want to have in your tool to help with the pollination of bell-shaped flowers? ASK Stem Activity 127
• What does your design look like? • In your opinion, what kind of design or method is best to help with the pollination of bell-shaped flowers? • Other than the materials suggested, what other materials do you need? List them and prepare them. • Draw a design and list down the steps on how to make the tool. IMAGINE PLAN 128 Hands-on Science Primary 5
• Create your tool based on what you plan. • Write down how your tool can help with the pollination of bellshaped flowers. • Are you satisfied with the tool you created? How do you modify it to make it better? • Test it again. • What is your conclusion about your improved version? Present your design and share with your classmates on how your tool can help with the pollination of bell-shaped flowers. CREATE IMPROVE PRESENT Stem Activity 129
STEM Activity A buzz wire circuit game A closed circuit is a complete path that electricity can flow through. An electric circuit is made up of a source of electricity, connecting wires and other components such as a switch and a bulb. These are called the components of the circuit. We use electricity virtually every minute. You are required to search for information regarding the making of a buzz wire circuit game. Analyze it, then design and create a better buzz wire circuit game. Do not forget to set the rules for your new game. Suggested materials: Copper tube Foam board Cardboard Wires with crocodile clips Bulb holder Battery holder Batteries Light bulbs Buzzer • What is the aim of this activity? • What do you need to know to get started? • What are the characteristics that you want to have in your buzz wire circuit game? ASK 130 Hands-on Science Primary 5
• What are your possible designs? • In your opinion, what kind of design is the best that you can make? • Other than the materials suggested, what other materials do you need? List them and prepare them. • Draw a design that you think is a better buzz wire circuit game. IMAGINE PLAN Stem Activity 131
• Build your buzz wire circuit game based on your design in the planning stage. • Write down the rules of the game. • If it does not work well, how do you modify it to make it better? • Test it again. • What is your conclusion about your improved version? Present in class on how you built the buzz wire circuit game. You can present it via a PowerPoint presentation. CREATE IMPROVE PRESENT 132 Hands-on Science Primary 5
Textbook PRIMARY 5 Hands-on Science Primary 5 comprises: • Textbook • Workbook AFFECTIVE DOMAIN SCIENCE TEACHING AND LEARNING This domain deals with pupils’ feelings and attitudes. Teachers evaluate pupils by observing their behavior and asking them questions when they carry out the activities. The ability to handle physical objects in a science laboratory is developed in this domain through the two special features: • Let’s Try! • STEM Activity PSYCHOMOTOR DOMAIN COGNITIVE DOMAIN The intellectual aspects of learning are enhanced in the six levels, i.e. remembering, understanding, applying, analyzing, evaluating and creating. Pupils can develop their knowledge of science through all the special features in this book. Hands-on Science Textbook is written to promote pupils’ learning. All activities in this book are designed to be pupil-centered. The book is designed to help pupils to: • Acquire their knowledge and understanding to scientific concepts and theories through inquiry learning • Master the scientific skills that are essential in the learning of science • Develop and inculcate scientific attitudes and noble values when carrying out the activities • Equip themselves with essential skills towards 21st century learning through STEM activities JBRB191045 ISBN: 978-981-14-7010-3