/ ^ Vocabulary natural resource, C38 renewable resource, C40 nonrenewable resource, C41 pollution, C42 esources Why do miners dig deep into Earth? They are looking for useful materials, such as metals, coal, or diamonds. Useful materials are called resources. Mining changes the land. People have been trying to repair the land. How do you think mining can change Earth? Process Skill You infer when you form an idea from facts or observations. C 36
,. Explore Activity How Does Mining Affect the land? Procedure Q Observe Place the cookie on the paper towel. Draw the cookie, and label its parts. The chips represent resources. The cookie represents the land. 0 Model Use toothpicks to try to remove the chocolate chips. Try to remove them without damaging the rest of the cookie. H Experiment Mine all the resources from the land. Q Observe Draw the cookie again. Drawing Conclusions How did mining change the cookie? If you needed more resources than you found in the land, how could you get them? Infer What are some problems people face when they mine resources from Earth? Going Further: Infer How can damage to mining areas be repaired? Materials chocolate chip cookie 4 toothpicks paper towel C37
Main Idea Earth's resources should be used wisely. What Is a Natural Resource? A natural resource (NACH-uhr-uhl REE-sawrs) is material on Earth that is necessary or useful to people. You use natural resources every day. They keep you alive or make your life better. Some natural resources come from the air. You take in oxygen, a gas in the air, when you breathe. Other natural resources come from Earth's surface. Soil is an important resource. Plants grow in soil. All animals need plants for food. Plants and animals are also natural resources. We use them for food, clothing, and many other things. These oil wells pump oil from deep underground. Oil is found in only a few places on Earth. Oil is refined into gasoline.
m -\% ' t.»:f»" < V " Why are plants and animals important natural resources? Still other natural resources come from below the surface. Fuels such as coal and oil are examples. Minerals such as iron, salt, and copper are, too. Sometimes people dig very deep into the ground to get these resources. Water is a natural resource that is found above, on, and below Earth's surface. Water is a gas in the air. It falls to the surface as rain or snow. Some of it soaks into the ground, becoming groundwater. Water is one of the most important resources. What natural resources are being shown in these pictures?
Treated properly, the soil will support crops year after year. What Is a Renewable Resource? A renewable resource (ri-new-uh-buhl REE-sawrs) is a resource that can be replaced or used over and over again. Soil and water are both renewable resources. Farmers grow crops in soil year after year. Sometimes strong winds blow away soil. Water can wash away soil, too. While soil can be used over and over again, it takes a long time for new soil to form. It is difficult to replace lost or damaged soil. Farmers need to know how to care for soil. Plants, animals, and water are also renewable resources. New plants are grown. New animals are raised to replace those that we use. Water moves from one part of Earth to another in the water cycle. What are three renewable resources? Like other plants, trees are a renewable resource. New trees can be planted to replace the ones we use.
What Is a Nonrenewable Resource? A nonrenewable resource (nahn-ri-new-uh-buhl REE-sawrs) is a resource that cannot be reused or replaced easily. Once a nonrenewable resource is used up, we cannot get more of it. Nonrenewable resources include minerals, such as gems and metals. People value gems for their beauty and strength. Metals are very useful. Iron and copper are metals. Fossil fuels are also nonrenewable resources. Coal, oil, and natural gas are examples. Fossil fuels take billions of years to form. They also can be hard to find. Once we find fossil fuels, we often do not keep them for long. We burn them for energy. Then they are gone forever! Gems are beautiful rocks What are two examples of nonrenewable resources? Most cars and trucks burn gasoline. Gasoline is made from fossil fuels. Will we always be able to get more gasoline? C41
What Is Pollution? As we use Earth's water, air, and land, we add materials to them. When you wash your hands/ you rinse soap and dirt into the water. Later, the water is cleaned. Soap and dirt are removed from the water. Sometimes Earth's resources are not cleaned. The result can be a problem called pollution (puh-lew-shuhn). Pollution occurs when harmful materials get into water, air, or land. When resources are polluted, they may be unsafe to use. Some pollution happens naturally. The water in a lake can become polluted when too much sand or soil settles in it. The lake may become a poor home for fish and plants. Volcanoes and forest fires pollute the air with dust, gas, and ashes. Humans cause pollution, too. People add things such as soap and fertilizers (FUR-tuh-ligh-zuhrz) to water. Fertilizers help plants grow, but they can soak into the ground and pollute water supplies. Smog is a kind of air pollution. It is a mixture of fog and smoke. * Forest fires cause air and land pollution. Forest fires can occur naturally, or they can be started by humans. C42
Air pollution is a problem in many cities. Cars, airplanes, and factories may add harmful gases and other materials to the air. Rain may bring these materials to Earth. The polluted rainwater may damage trees and buildings, and pollute water supplies. Land pollution can be a problem, too. As Earth's population grows, people produce more trash. Trash takes up valuable space. All living things use Earth's resources. Cleaning up pollution is always a good thing to do. READING Sequence of Events What is one way the water supply can become polluted? In the past many people dumped their trash into rivers. Now it is against the law. FOR SCHOOL OR HOME Cleaning Water BE CAREFUL! Wear goggles. 1. Model Place a funnel inside the bottom half of a plastic bottle. Put a layer of gravel in the funnel, and cover it with a layer of sand. 2. Mix a cup of water with a little soil and some crushed leaves. Slowly pour the mixture into the funnel. 3. How did the mixture change as it went through the funnel? 4. How does Earth clean water? C43
7 f v ^H^^I^^H One Person's Trash in a Year \ 0 10 Pounds 20 30 40 50 60 70 80 90 100 Plastic Tin cans Aluminum cans How many pounds of each kind of trash does this person produce? How Can You Conserve Resources? If we all conserve Earth's resources, we can keep using them in the future. One way to conserve resources is to reduce our use of them. To reduce is to use less of something. Try to reduce your use of paper. Use all the pages in a notebook before buying a new one. Another way to conserve resources is to reuse them. To reuse is to use something again and again. You might reuse grocery bags or glass jars. A third way to conserve is to recycle. To recycle is to treat something so that it can be used again. Glass, paper, plastic, and metals can all be recycled. What are three ways to conserve resources? Recycling lets you use something again. Do you recycle? C 44
Lesson Review Why It Matters Every year more and more people live on Earth. However, Earth's supply of resources stays the same or goes down. We keep losing many nonrenewable resources, such as fossil fuels. Everyone should conserve resources. That means using resources wisely. If we conserve, we can keep using Earth's resources. Think and Write 1 Give three examples of a natural resource. Discuss how each resource is used. 2. Why is water a renewable resource? 3. Why are fossil fuels a nonrenewable resource? 4. Discuss three ways to conserve resources. 5. Critical Thinking You bought a present for your friend's birthday. How could you wrap the present in a way that conserves paper? LITERATURE LINK Read The Old Swimming Hole a story about how Nick discovers a swimming hole has become a garbage dump. Think about something you can do to stop pollution. Try the activities at the end of the book. Make a poster. Design a poster to explain about recycling. Use the poster to tell people about recycling or to urge people to recycle cans, plastic, or paper. MUSIC LINK Write a song. Gasohol is a mixture of gasoline and ethanol, which comes from corn. Gasohol helps corn farmers and saves gasoline, too. What if you work for a company that makes gasohol? Write a song to tell people about this product. TECHNOLOGY LINK At the Computer Visit www.mhscience02.com for more links. C45
An electric car travels down a road. C46 Electric Powered This electric battery powers the car.
D NATIONAL GEOGRAPHIC Most cars today run on gasoline a mixture of fossil fuels. However, fossil fuels may run out someday. Burning fossil fuel pollutes the air, too. Are there other ways to power a car? Yes, there are. Cars can run on electricity! Electric cars receive power from batteries. Instead of filling a tank with gasoline, the driver recharges the batteries. Some electric cars use a little gasoline, too. The gasoline helps the batteries last longer. Scientists have been studying electric cars for a long time. They are looking for ways to improve the cars and to build them more cheaply. By the time you learn to drive, you may be driving an electric car! A rechargeable battery powers this car. Today's vehicles rely on gasoline. Write ABOUT IT 1. What are the benefits of electric cars? 2. Do you think you will be driving an electric car someday? Why or why not? Visit www.mhscience02.com to learn more about cars. C47
Chapter 5 Review Vocabulary Fill each blank with the best word from the list. condense, C31 conserve, C34 evaporate, C31 fossil, C22 fuel, C26 mineral, C6 natural resource, C38 nonrenewable resource, C41 pollution, C42 soil, C14 1. A substance found in nature that is not a plant or an animal is a(n). 2» _ is a mixture of tiny rocks, minerals, and decayed materials from plants and animals. 3. The imprint or remains of something that lived long ago is a(n). 4. Something that is burned for its energy is called a(n). 5. A material from Earth that is useful or necessary is a(n) _ 6. Coal is a(n) because it cannot be reused or replaced in a useful amount of time. 7. Smoke from a fire can cause air C48 8* To use something wisely, not wastefully is to _ 9. 10. Two parts of the water cycle are when water: Test Prep 11* The building blocks of rocks are. A minerals B quartz C living things D soil 12. Which of the following is true about fossils? F They tell us about plants of the past. G They tell us about animals of the past. H They tell us how Earth has changed. J All of the above. 13. Most of Earth's water is found in A lakes B rivers C glaciers D oceans
14. Natural gas and oil are _ F renewable resources G minerals H nonrenewable resources J formed by glaciers 15. Treating old materials to make them into new products is. A recycling B pollution C weathering D reusing Concepts and Skills 16. Reading in Science Look at the chart on page C9. Describe the three main ways that rocks form. 17. Critical Thinking What if you are going to plant some seeds? Why might you add humus to the soil? 18. Process Skills: Measure Look at the graduated cylinder. How many milliliters of water does it hold? 19. Product Ads The labels of some laundry soaps tell you that the soaps break down into harmless materials. Why is this good for something that will be put into water? 20. Scientific Methods Your kitchen has a leaky faucet. How can you find out how much water is wasted each day? Boost your test scores Be Smart! Visit www.mhscience02.com to learn more. C 49