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Copyright © by Harcourt, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to School Permissions and Copyrights, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida 32887-6777. Fax: 407-345-2418. HARCOURT and the Harcourt Logo are trademarks of Harcourt, Inc., registered in the United States of America and/or other jurisdictions. Printed in the United States of America ISBN-13: 978-0-15-349166-5 ISBN-10: 0-15-349166-3 1 2 3 4 5 6 7 8 9 10 179 15 14 13 12 11 10 09 08 07 06 If you have received these materials as examination copies free of charge, Harcourt School Publishers retains title to the materials and they may not be resold. Resale of examination copies is strictly prohibited and is illegal. Possession of this publication in print format does not entitle users to convert this publication, or any portion of it, into electronic format.
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Adaptations Lessons 4–6 Lesson 4 How Do Living Things Change Environments? . . . . . . . . . . . . . . . . . . . . . . 2 Lesson 5 How Do Changes to Environments Affect Living Things?. . . . . . . . . . . . . . . . . 8 Lesson 6 How Have Living Things Changed over Time? . . . . . . . . . . . . . . . . . . . . . . . . 14 VisitVisit The Learning Site!The Learning Site! wwww.harcourtschool.comww.harcourtschool.com
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444 How DoHow Do VOCABULARY Living ThingsLiving Things pollution ChangeChange Environments?Environments? 2
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READING FOCUS SKILL SEQUENCE When you sequence things, you put them in order. See if you can follow the sequence of changes in the environment. See what comes first. Then see what happens next. People Harm the Environment People change the environment. Some changes cause harm. People cut down trees. This harms living things that need trees. Animals may lose their homes. Some may die. People change the environment when they build roads. 4
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People also make pollution. Smoke from factories is a kind of air pollution. An oil spill is a kind of water pollution. Animals that get covered with oil may die. What happens to some animals after trees are cut down? Big machines may take away some animal homes. 5
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People Help the Environment Some changes people make can help the environment. After trees are cut down, people can plant new trees. Then forests can grow back faster. Cars cause air pollution. Special car parts are now made so that cars cause less pollution. After people cut down trees, how can they help the forest grow back? A tunnel can give animals a safe way to cross roads. 6
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Living Things Change Their Environments Animals change their environments. Some animals dig holes. Beavers build dams to form ponds. The ponds become homes for other animals. Plants change their environments, too. Some pond plants grow very fast. They block sunlight from plants below. These plants may not survive. What happens when pond plants grow very fast? Beavers build ReviewReview dams. C Complete these sequence statements. 1. After trees are cut, many animals must find new ______ . 2. Parts were added to cars, which decreased air ______ . 3. After a dam is built, a ______ forms behind it. 4. If pond plants grow very fast, the ______ cannot reach plants below. 7
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55 How DoHow Do VOCABULARY Changes toChanges to drought EnvironmentsEnvironments balance Affect LivingAffect Living Things?Things? A drought is a long time with very little rain. 8
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READING FOCUS SKILL CAUSE AND EFFECT A cause is something that makes another thing happen. An effect is the thing that happens. Look for examples of cause and effect. Find what causes balance to change. Tell what happens. Climate Affects Living Things Different environments have different climates. Animals have adaptations that help them survive in their climates. During a drought, there is little rain for a long time. Some plants are used to getting a lot of water. During a drought, these plants may die. A Water helps Plants may people stay die in a cool in hot drought. C climates. 10
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The desert is hot and dry. Few animals can live there. Those that do have special adaptations. Desert plants grow very fast when it rains. They make seeds quickly before the land dries up again. What effect can a drought have on plants? Plants can die during a flood when a river overflows. 11
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Fire Affects Living Things Forest fires change the environment. Many trees and other plants burn. Some animals lose their homes. If they cannot find new homes, they may die. Fires can be good for forests, too. Burned trees often fall. This lets the sun reach small plants on the ground. More light helps them grow better. How can fires cause some plants to grow better? Fires both harm and help animals. 12
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Balance Between Living Things Balance means having not too many and not too few of each thing. Environments need the right numbers of the right plants. Without them, animals will not have the foods they need. They will have to move or die. This pond environment is in balance. It has plants and animals in the right amounts. What is the effect of having too few plants in an environment? A pond environment in balance ReviewReview Complete these cause and effect statements. 1. A ______ causes plants to dry up. 2. When plants dry up, they often ______ . 3. A drought can cause forest ______ . 4. Fires help keep the ______ of not too many of one kind of plant or animal. 13
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666 How HaveHow Have VOCABULARY LivingLiving fossil extinct ThingsThings ChangedChanged over Time?over Time? Fossils help us learn about plants and animals that lived long ago. 14
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READING FOCUS SKILL COMPARE AND CONTRAST You compare when you look at how things are alike.You contrast when you look at how things are different. Compare and contrast extinct and living plants and animals. How are they alike and different? Animals Then and Now Fossils are remains of plants or animals that died long ago. They are very hard. Some fossils are animal parts, such as bones or teeth. Others are just prints left in mud. Tyrannosaurus rex 16
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This fish was thought to be extinct. Fossils show how animals have changed. No animals today look like dinosaurs. Camels today look much the same as camels long ago but are larger. Compare camels today to extinct camels. The fish was found to still be living today. 17
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Plants Then and Now There are more animal fossils than plant fossils. Plants are soft and do not last well. Some plants left leaf prints in mud. The prints became fossils. Some fossils were once tree trunks that became like stone. Fossils show that some kinds of plants no longer grow on earth. Other fossils look like plants that still live today. Compare plant fossils to animal fossils. A fern fossil 18
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