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Transcript of "Grade5"
1. Student Inquiry Lesson Sheets Grade 5
Copyright © by Houghton Mifflin Harcourt Publishing Company All rights reserved. No part of the material protected by this copyright may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, broadcasting or by any other information storage and retrieval system, without written permission of the copyright owner unless such copying is expressly permitted by federal copyright law. Only those pages that are specifically enabled by the program and indicated by the presence of the print icon may be printed and reproduced in classroom quantities by individual teachers using the corresponding student’s textbook or kit as the major vehicle for regular classroom instruction. HOUGHTON MIFFLIN HARCOURT and the HMH Logo are trademarks and service marks of Houghton Mifflin Harcourt Publishing Company. You shall not display, disparage, dilute or taint Houghton Mifflin Harcourt trademarks and service marks or use any confusingly similar marks, or use Houghton Mifflin Harcourt marks in such a way that would misrepresent the identity of the owner. Any permitted use of Houghton Mifflin Harcourt trademarks and service marks inures to the benefit of Houghton Mifflin Harcourt Publishing Company. All other trademarks, service marks or registered trademarks appearing on Houghton Mifflin Harcourt Publishing Company websites are the trademarks or service marks of their respective owners.
Contents Unit 1 How Scientists Work Lesson 2 How Do Scientists Learn About the Natural World? .......................................19-22 Lesson 4 How Do You Perform a Controlled Experiment? .............................................39-40 Lesson 6 How Can Scientists Learn from Observations? .................................................55-56 Unit 2 The Engineering Process Lesson 2 How Can You Design a Solution to a Problem? .................................................79-80 Lesson 4 How Can You Use Engineering to Solve a Problem? ...................................…..95-96 Unit 3 Cells to Body Systems Lesson 2 How Can We Observe Cells? .........................................................................123-124 Lesson 6 How Does the Body Stay Cool? .....................................................................167-168 Unit 4 Living Things Grow and Reproduce Lesson 2 What Is a Dichotomous Key? ......................................................................... 189-190 Lesson 4 What Factors Affect Germination Rate? .........................................................207-208 Unit 5 Ecosystems Lesson 2 What Makes Up a Land Ecosystem? .............................................................261-262 Lesson 4 How Does Drought Affect Plants? ...............................................................283-284 Unit 6 Energy and Ecosystems Lesson 3 What Role Do Decomposers Play? .............................................................321-322 Unit 7 Natural Resources Lesson 3 How Can We Conserve Resources? ...........................................................357-358 Unit 8 Changes to earth’s Surface Lesson 2 How Does Water Change Earth’s Surface? ..........................……………...385-386 Lesson 4 How Do Plates Move? ................................................................................ 405-406 Unit 9 The Rock Cycle Lesson 2 What Are Properties of Minerals? ...............................................................425-426 Lesson 4 How Can You Model Changes in Rock?......................................................445-446 © Houghton Mifflin Harcourt Publishing Company
Unit 10 Fossils Lesson 3 How Can Scientists Use Fossils? .................................................................483-484 Unit 11 Earth’s Oceans Lesson 3 How Can We Model Ocean Water? .............................................................517-518 Unit 12 The Solar System and the Niverse Lesson 2 How Do We Observe Object s in the Solar System? ..................................559-560 Unit 13 Matter Lesson 2 How Does Water Change?...........................................................................595-596 Lesson 5 What Affects the Speed of Dissolving? .....................................................627-628 Unit 14 Light and Sound Lesson 2 How Does Sound Travel Through Solids, Liquids, and Gases? ..............…665-666 Lesson 5 What Happens When Light Is Reflected? .................................................691-692 Unit 15 Forces and Motion Lesson 2 How Do Forces Affect Motion? ..................................................................719-720 Lesson 3 What Are Balanced and Unbalanced Forces? ..............................................721-722 © Houghton Mifflin Harcourt Publishing Company
How Do Scientists Learn About the Natural World? Scientists learn about the natural world by making observations and performing investigations. In this activity, you’ll compare predictions made with—and without—using scientiﬁc evidence. Use the origami predictor to forecast, or predict, the weather for the next week. Then find the forecast made by a scientist. Record both forecasts. Materials origami weather predictor sheet scissors pencil weather forecast from a newspaper Inquiry Flipchart page 3 For one week, compare the actual weather to both forecasts. Tear out the origami weather predictor sheet from your student book. Think about the weather where you live. Write eight different weather predictions. One prediction might be sunny, windy, and hot. 2 A Word for the Wise Evidence is information, such as observations, that scientists collect and use to draw conclusions and make predictions. Follow the directions to make the origami weather predictor. Name Essential Question How Do Scientists Learn About the Natural World? Set a Purpose Think About the Procedure What will you learn from this investigation? How did you choose what predictions to write on your origami predictor? Record Your Data In the table below, record your results. © Houghton Mifflin Harcourt Publishing Company Date Origami Prediction Weather Service Prediction Actual Weather 19
Draw Conclusions Of the two kinds of weather predictions, which one was more likely to be correct? Explain. 4. The line graph shows average October air temperatures in Houston, TX. Can you predict the air temperature in Houston next October? If so, how? Average Temperature in Houston in October Analyze and Extend 1. What results do you think you would get if you continued your investigation for a whole month? Average High Temperature (°F) 90° 86° 82° 78° 74° 70° 0 1 2. How do you think the weather service makes its predictions? 6 11 16 21 Day of Month 26 31 5. What else would you like to find out about how scientists make predictions? Write each idea as a question. 20 © Houghton Mifflin Harcourt Publishing Company 3. Why is it important that scientists make good weather predictions?
2 Directions 1. Carefully tear this page out of your book. 2. Cut out the square below. You will use it to make your origami weather predictor. 3. On each set of lines, write a weather prediction. S t io n 2 5 W ea th er 1 8 6 7 t s ca re Fo © Houghton Mifflin Harcourt Publishing Company y nn u 4 c Pr e di 3 4. Follow the instructions on the back of this page to fold and use your origami weather predictor. 21
Directions (continued) 5. Fold the blue dots into the blue circle. Turn the paper over, and fold the green dots into the green circle. 6. Fold the paper in half so that the yellow dots touch each other. Make a crease, and unfold the paper. Fold it in half again so that the pink dots touch each other. 22 © Houghton Mifflin Harcourt Publishing Company 7. Put your fingers under the colorful squares. With your group, make a plan to use this tool to predict the weather.
4 How Do You Perform a Controlled Experiment? A controlled experiment takes thought, care, and time. Let’s see if you have what it takes! Find two more types of surfaces to test. Repeat Steps 1 and 2. Materials small ball meterstick various floor surfaces For each surface, find the average of the five trials. Inquiry Flipchart page 5 Place a meterstick against a wall so that the 0-cm mark touches the floor. Record what the floor is made from. Drop the ball from the 100-cm mark. Record the height the ball bounces. Do this five times. A Word for the Wise A controlled experiment is one in which the procedure is repeated, changing only one condition each time. Name Essential Question How Do You Perform a Controlled Experiment? Set a Purpose Think About the Procedure What will you learn from this experiment? What is the tested variable in this experiment? Each time you try the same test, it is called a trial. Why is it important to do repeated trials of this experiment? Record Your Data In the table below, record your results. © Houghton Mifflin Harcourt Publishing Company Surface Material Trial 1 Trial 2 Height Ball Bounced Trial 3 Trial 4 Trial 5 Average 39
Draw Conclusions What can you conclude based on your experiment? 3. Tennis is played on three types of surfaces: grass, packed clay, and hard courts. Hard courts are often made from asphalt, the black road surface material, with paint on top. Predict how these surfaces would affect ball bounces. Then do some research. Find out the pros and cons of each type. Analyze and Extend 1. Think about the materials the ball bounced on. What was it about them that affected the height of the bounce? 4. What else would you like to find out about how balls bounce? 40 © Houghton Mifflin Harcourt Publishing Company 2. What other floor materials could you test? Predict the results.
How Can Scientists Learn from Observations? Sometimes you can’t do an experiment. But you can still answer questions by investigating. In this activity, you’ll learn about soils by simply making observations. Place 100 mL of soil in a coffee filter. Find and record its mass. Place the filter in a mesh sieve above a small container. Fill a graduated cylinder with 100 mL of water. Slowly pour water onto the soil. When the soil can no longer hold water, record the amount you poured. Materials soil sample white paper measuring spoons hand lens measuring cup coffee filter pan balance mesh sieve small container graduated cylinder paper bag Inquiry Flipchart page 7 On a sheet of white paper, place a teaspoon of soil. Use the hand lens to observe it. Record your observations. Place 200 mL of soil in a paper bag, and record the mass of the bag. Place the bag in a dry place for a week. Then find the bag’s mass again. 6 Compile your data in a class data table. In a small group, discuss ways to classify the soil samples. Name Essential Question How Can Scientists Learn from Observations? Set a Purpose What will you learn from this investigation? Think About the Procedure What planning must I do before this investigation? What tools are used in this investigation. What measurements, if any, are taken with them? Record Your Data In the space below, record your results. Soil Sample: © Houghton Mifflin Harcourt Publishing Company My Observations: Amount of water held by 100 mL of soil: Mass Before Drying: Mass After Drying: 55
Compare your data with the data from other groups. What can you conclude? Analyze and Extend 1. Why is it important that soils be able to hold some water? 2. Why would a farmer want to know about the soil on his or her farm? 56 3. How was this investigation different from a controlled experiment? 4. Why was it important to know the mass of the soil before it was dried for one week? 5. What else would you like to find out about different types of soils? © Houghton Mifflin Harcourt Publishing Company Draw Conclusions
How Can You Design a Solution to a Problem? Suppose you wanted to build a raft to carry a heavy load. What would you do? In this activity, you will design and test a model of a raft. Float your raft on water. Test it to see how much cargo it can hold. Carefully add pennies one at a time to your raft until it sinks. Materials balance modeling clay plastic container with water in it 10 or more pennies paper towels Measure 60 grams of modeling clay. Shape the clay into a raft. Test your raft in water. If your raft doesn’t float, reshape it until it does. In your notebook, sketch a diagram of your raft loaded with pennies. Inquiry Flipchart page 9 Record how may pennies you added before your raft sank. Find a way to carry more pennies. Try a different design for your raft or place the pennies in a different way. Test your new design and record your observations. 2 A Word for the Wise MODEL: a model is used to represent something real that is too big, too small, or too complex to study directly Name Essential Question How Can You Design a Solution to a Problem? Set a Purpose Think About the Procedure What is the purpose of this investigation? What variables can affect the results of this investigation? State Your Hypothesis © Houghton Mifflin Harcourt Publishing Company Sketch a raft with pennies on it to show what you think will be the best design. Write a brief description of your raft’s key features. Record Your Data In the space below, make a table in which you record your results. Be sure to include information about each raft design and the number of pennies and their placement. 79
Draw Conclusions Why did some of your model rafts work better than others? 2. Mary and Sarah built identical raft models. Mary’s raft sank after adding only 6 pennies. Sarah’s raft held 12 pennies before it sank. Suggest a possible reason for the difference. Analyze and Extend 1. Sketch a raft design you think would NOT float. Explain why. 3. Scientists often build and test models to solve problems. What are the advantages of solving problems in that way? 80 © Houghton Mifflin Harcourt Publishing Company 4. Think of other questions you would like to ask about designing solutions to a problem.
How Can You Use Engineering to Solve a Problem? Engineers solve a problem using the design process. In this activity, you’ll use that same process to design and build a prototype that solves the problem of a hard-to-open jar. Materials 2 wood slats, with holes 2 pieces sandpaper plastic tubing rubber belt masking tape glue wing nut and bolt small jar with lid medium jar with lid large jar with lid scissors Look carefully at the materials provided. Think about how they could be used to make a jar opener. With a partner, brainstorm ideas. Sketch each of your ideas, and make notes as to how you think each design might work. List the pros and cons of each design. Choose the design you think will work best. Record a detailed plan for making your prototype. Be sure to keep notes and make drawings of your design. Build your prototype jar opener. Be sure to make a detailed drawing of your final prototype. Label the materials you used, and explain how you put it together. Inquiry Flipchart page 11 Identify the criteria you will use to test your prototype. Test your prototype. Record how well it worked. 4 Make improvements to your design if needed.Test your jar opener again. 11 Name Essential Question How Can You Use Engineering to Solve a Problem? Set a Purpose Record Your Data What problem are you trying to solve? Draw a detailed plan for your jar opener. Label the materials. Describe how it will work. Then build and test your prototype. How would a jar opener be useful? Think About the Procedure What is a prototype? © Houghton Mifflin Harcourt Publishing Company Describe two ideas for your prototype. 95
Draw Conclusions What criteria did you use to test your prototype? 2. Summarize how you designed and tested your jar opener. Describe how you tested your prototype. Record any data you collected. 3. Describe another jar opener design that is possible using the materials provided. Analyze and Extend 1. Did your prototype need improvements? Describe them. 96 © Houghton Mifflin Harcourt Publishing Company 4. Think of other designs you might make if you had different materials. How would that design work?
How Can We Observe Cells? Plant and animal cells have different parts. Do the cells look different under a microscope? In this activity, you will observe plant and animal cells to ﬁnd out. Materials apron dropper red food coloring microscope slide onion slice tweezers cover slip paper towel microscope colored pencils prepared slide of animal cells Put on your apron. Use the dropper to place one drop of food coloring on the center of a slide. Break the onion slice, and use the tweezers to pull off a piece of onion skin. Put the onion skin in the drop of food coloring. Gently lower the cover slip at an angle so that it spreads the food coloring. CAUTION: Be careful when handling the glass slides. Remove any excess food coloring with a paper towel. Inquiry Flipchart page 14 Observe the onion skin cells under a microscope. Use colored pencils to make a drawing of what you see. 2 Observe the prepared slide of animal cells. Use the colored pencils to draw what you see. Wash your hands when you are finished. 14 Name Essential Question How Can We Observe Cells? Set a Purpose What is this directing structure called? What will you be looking for in this activity? Record Your Observations Drawing of Plant Cell What is the purpose of using food coloring to look at the plant cell? © Houghton Mifflin Harcourt Publishing Company HMH Credits Think About the Procedure When scientists observe, they use their senses to learn about objects and events. In the center of most cells are structures that direct how the cells function. Look for these structures. Based on what you observe, how many directing structures does each cell have? Drawing of Animal Cell 123
Draw Conclusions What similarities do you observe between the two cells? What differences do you observe between the two cells? 2. Do you think other parts of the onion would look the same as the skin? 3. You observe a piece of tissue under the microscope. Each cell of the tissue has a cell wall, a cell membrane, a nucleus, and organelles including chloroplasts and vacuoles. What type of organism did this tissue come from? How do you know? Why do you think a plant cell has a thicker outer covering than an animal cell? 4. What other questions would you like to ask about cells? Analyze and Extend 124 5. Name two ways you could find the answer to your questions. © Houghton Mifflin Harcourt Publishing Company HMH Credits 1. Suppose that you found a mystery organism. How could you tell if it was a plant or an animal?
How Does the Body Stay Cool? When you are hot, you sweat. This allows your body to cool off. In this activity, you will explore what happens as three towels cool. Think about how this relates to your body’s cooling system. Materials 3 paper towels 3 thermometers 3 paper plates marker graduated cylinder water rubbing alcohol fan Make sure the water is at room temperature. Measure 50 mL of water. Pour the water on the paper towel on the plate labeled Water. Inquiry Flipchart page 18 Obtain 50 mL of rubbing alcohol from your teacher. Pour it on the paper towel on the plate labeled Alcohol. Label the plates Dry, Water, and Alcohol. Record the starting temperature of each thermometer. 6 Place all three plates in front of the fan. Record the temperature on each thermometer every minute for five minutes. Wrap a paper towel around the bottom of each thermometer. Place each thermometer on a plate. CAUTION: Be sure to protect your eyes from splashing liquids. Keep alcohol away from flames. 18 Name Essential Question How Does the Body Stay Cool? Set a Purpose Record Your Data What will you learn from this experiment? Record your observations in a data table. State Your Hypothesis Write your hypothesis, or testable statement. Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Which sample is the control? What is its purpose? Draw Conclusions How did your results compare with your hypothesis? 167
Analyze and Extend 1. What was the difference between the starting temperature and the ending temperature for each of your experimental groups? Show your work in the space below. 2. Make a bar graph in the space below to display your data. 4. A swamp cooler is a type of air conditioner that blows air over a wet surface. Use your data to explain whether you think this would be an effective way to cool a building. 5. Why is it important that your body be able to cool itself? 6. Think of other questions you would like to ask about evaporation and cooling. 168 © Houghton Mifflin Harcourt Publishing Company 3. How does this activity relate to the role of sweating?
What Is a Dichotomous Key? Beans have different characteristics. In this activity, you will classify a group of beans and make a dichotomous key. Your classmates will use your key to identify the bean groups. Materials 6 beans in a bag Get a bag of beans from your teacher. Draw a dichotomous key that includes the names of all six beans. If you do not know their names, you can number the beans or identify them in some other way. Fill out your dichotomous key with yes or no questions that will enable you to classify all six beans. Inquiry Flipchart page 20 Pour out the beans onto your desk. Observe the beans. What differences do you notice? Make a list of characteristics that you observe about the beans. 2 Give your dichotomous key to a classmate. Give the classmate a few beans from your bag. Ask your classmate to identify the beans he or she has by using your key. 20 Name Essential Question What Is a Dichotomous Key? Set a Purpose Think About the Procedure What will you learn from this investigation? Why are the beans you are given different from one another? Record Your Data © Houghton Mifflin Harcourt Publishing Company In the space provided, make your dichotomous key using the bean characteristics you identified. 189
Draw Conclusions Scientists classify and organize living things based on how they are similar or different from one another. Why is it important for scientists to use the same characteristics to classify living things? 2. Compare charts with a classmate. Was one chart easier to use than the other chart? 3. How might grouping and classifying things, rather than just describing them, make it easier for others to identify the things? Scientists must be very specific when describing living things. Why might scientists want to avoid using terms such as small, big, heavy, and light when classifying living things? 4. How was the dichotomous key you made to classify beans different from dichotomous keys scientists use to classify organisms? Analyze and Extend 190 5. What other questions would you like to ask about how scientists use dichotomous keys? © Houghton Mifflin Harcourt Publishing Company 1. Which characteristics did you use to classify the beans? Which characteristics did your classmates use?
What Factors Affect Germination Rate? Every type of plant grows best in certain conditions. In this experiment, you will ﬁnd out which conditions are best for the growth of bean seeds. To test how light affects germination rate, place one cup under a shoe box. Label this cup A. Place another cup in a lit area, such as a windowsill. Label this cup B. Every day, add about 60 mL of water to both cups. Materials 5 plastic cups potting soil plastic gloves graduated cylinder CAUTION: Wear plastic gloves when handling potting soil. Place 8 cm of potting soil in each of the five plastic cups. shoe box bean seeds water ruler To test how water affects germination rate, place the three remaining cups in a lit area, such as a windowsill. Label the cups C, D, and E. Do not add water to cup C. Every day, add about 40 mL of water to cup D and 80 mL of water to cup E. Inquiry Flipchart page 23 Place three or four bean seeds on top of the soil in each cup. Then sprinkle 3 cm of soil on top of the seeds in each cup. 4 Observe the cups daily. Record any changes you see. 23 Name Essential Question What Factors Affect Germination Rate? Set a Purpose Record Your Data Why is it important to know the factors that affect germination? In the space below, make a table to record your observations. Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Which two factors are you testing in this activity? 207
Draw Conclusions 2. How could you test this factor? Which plants grew the most? Which plants grew the least? 3. What other questions would you like to ask about germination rates? How does light affect seed germination? How does water affect seed germination? 4. Choose one question you wrote and investigate it. Write a summary of your investigation. Analyze and Extend 208 © Houghton Mifflin Harcourt Publishing Company 1. What other factor do you think might affect germination?
What Makes Up a Land Ecosystem? If you were asked to list the living things around you, what would you list? You would probably list shrubs and trees, cats and dogs, birds, and maybe garden snakes. But what about those things living beneath your feet? Would you also list them? Materials meter stick 4 stakes string gloves magnifying glass or box collecting jars field guides Go out into the schoolyard, a nearby park, or a nature preserve. Select a study site where there is a variety of plants and soil coverings. In your study site, measure a 1 meter by 1 meter square area. Use the stakes and string to mark this sample area. Count and identify the producers and consumers you observe within your sample area. Record your observations. Inquiry Flipchart page 27 Caution! Make sure to wear gloves when doing this step. Carefully turn over any rocks, leaves, or twigs in your sample area. 2 Use the collecting jars, a magnifying glass or box, and field guides to observe, identify, and classify any organism that you may find. 27 Name Essential Question What Makes Up a Land Ecosystem? Set a Purpose What do you think you will learn in this activity? Why did you measure and mark your sample area? Record Your Data Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Why do you think your sample site should have a variety of plants and soil coverings? In the space below, make a table to record the different living things found in your sample site and their role in the ecosystem. 261
Draw Conclusions How did you determine the role that each living thing played? 3. Which role in the ecosystem had the greatest variety of living things? 4. In the space below, draw a picture of your sample area. Make sure to include an example of a producer and a consumer that you found living in it. Compare your results with the results of other groups. Explain any differences or similarities. Analyze and Extend 1. What kind of living things did you find in your sample area? 5. Think of other questions you would like to ask about how living things interact in the ecosystem. 262 © Houghton Mifflin Harcourt Publishing Company 2. Which role in the ecosystem had the greatest amount of living things?
How Does Drought Affect Plants? Materials A drought happens when a place gets much less rainfall than normal. What happens to plants when their environment changes and they do not get the usual amount of water? 5 plastic cups black marker 125 seeds potting soil water measuring cup Fill each cup with moist potting soil. Plant 25 seeds in each cup. Label the cups A through E. B Water the cups according to the following schedule: Make a hypothesis about how the seeds in the different cups will grow. Make a hypothesis about how the seeds in the different cups will grow. Inquiry Flipchart page 30 4 A Place the cups on a sunny cups for two weeks. 30 Name Essential Question How Does Drought Affect Plants? Set a Purpose What will you better understand about plants after doing this experiment? What part of the experiment did you change? Record Your Data State Your Hypothesis Write your hypothesis, or testable statement. Record your observations in the table below. Plant Observations Cup A Cup B © Houghton Mifflin Harcourt Publishing Company Think About the Procedure Cup C What parts of your experiment stay the same for each test group? Cup D Cup E 283
Draw Conclusions Was your hypothesis supported? Why or why not? 3. Suppose you are studying pea plants. You find that half of the individual pea plants are able to survive in mild drought conditions. Why might this data be imporant? What conclusions can you draw from this investigation? 4. How would you set up an experiment to test the following hypothesis: The amount of fertilizer does not affect how quickly plants grow. Draw and label a picture that shows your setup. Analyze and Extend 1. What natural conditions did Cup A and Cup E represent? 284 © Houghton Mifflin Harcourt Publishing Company 2. Did the plants in the cups that got the most water do the best? What can you infer based on your results? 5. Think of other questions you would like to ask about how environmental conditions affect plants.
What Role Do Decomposers Play? Decomposers break down dead plant and animal material. Mold—a type of fungus—is one kind of decomposer. In this activity, you will get to watch how mold changes bread. Use the spray bottle to gently mist the bread slice on plate A. Observe and record any changes. Materials 2 bread slices 2 paper plates hand lens spray bottle containing water 2 resealable plastic bags 2 paper bags Set the bread slices on paper plates labeled A and B. Study their appearance using a hand lens. Record your observations. Put the moist bread inside a resealable bag and label it A. Put the dry bread inside the other resealable bag and label it B. Place each resealable bag into a paper bag. Inquiry Flipchart page 34 Use the hand lens to observe the bread slices every day for about ten days. Record any changes you see. CAUTION! Do not open the plastic bags. Mold can be harmful. 3 Dispose of the bread as your teacher directs. 34 Name Essential Question What Role Do Decomposers Play? Set a Purpose How do you think decomposers change materials? Why do we spray one of the bread slices with water and not the other? Record Your Data Write a statement summarizing how you think mold changes the food it grows on. In the space below, make a table in which you record your observations. © Houghton Mifflin Harcourt Publishing Company Think About the Procedure What are different observations you can make about the appearance of the bread? 321
Draw Conclusions In the space below, draw a picture of the appearance of breads A and B during the last day of your investigation. 3. Did spraying the bread with water have any effect on how fast the mold grew? Explain. 4. What do you think would happen to the bread if you continued to let the mold grow on it? Did your observations indicate that mold is a decomposer? Explain. 5. Use your observations to describe the role of decomposers in the environment. 6. Think of other questions you would like to ask about decomposers. Analyze and Extend 2. Where do you think mold gets its nutrients from? 322 © Houghton Mifflin Harcourt Publishing Company 1. How did the mold change the bread?
How Can We Conserve Resources? Did you know that your notebook paper could be made from recycled materials? Recycling helps conserve trees and other natural resources. You can make recycled paper, too! For every 240 mL of water, add 16 mL of starch. Mix the mixture until a watery pulp forms. Dip the window screen into the mixture to coat one side with a layer of pulp. Carefully remove the screen. Hold the screen over the tub as the water drains. Materials safety goggles lab apron scrap paper plastic tub water metric measuring cup laundry starch egg beater pre-cut window screen newspaper dowel Place the screen between several sheets of newspaper. Roll the dowel over the top of the newspaper until all water is squeezed out. Inquiry Flipchart p. 38 3 CAUTION: Put on safety goggles and an apron. Tear the scrap paper into 2-cm strips. Put the strips into the tub and add water. Keep track of the amount of water you add. Let the pulp dry completely. Then carefully peel it from the screen. 38 Name Essential Question How Can We Conserve Resources? Set a Purpose Record Your Data What will you learn from this investigation? In the space below, describe the physical characteristics of the paper you made. Think About the Procedure © Houghton Mifflin Harcourt Publishing Company HMH Credits Why do you think starch is added to the pulp mixture? Why is it important to squeeze out the extra water? 357
Draw Conclusions Some of the paper you use now has been recycled from old paper. Draw conclusions about why people might choose to make paper from waste material instead of directly from trees. Analyze and Extend 3. How does recycling paper help the environment and living things? 4. What are some other ways scrap paper could be recycled? 1. Just as scientists do, you made a model to see how something might work on a larger scale. Using what you learned, suggest ways recycled paper might be made in a large factory. 5. How would you change your paper if you were to make it again? 358 © Houghton Mifflin Harcourt Publishing Company HMH Credits 2. How does the paper you made compare to the paper you use in school?
How Does Water Change Earth’s Surface? Some rock, such as limestone, erodes more easily than other rock that surrounds it. This leaves hollow spaces in the harder rock. In this activity, you will model how water forms caves. Inquiry Flipchart page 41 Materials plastic tray 9 sugar cubes modeling clay water book (about 4 cm thick) Arrange nine sugar cubes into a square on the tray. 2 Press the clay into a flat slab. Place it on top of the sugar cubes and press firmly so the clay sticks to the tray on two opposite sides of the cubes. Leave the other two sides of the sugar exposed so you can see it. Place the book under one end of the tray to form a slope. Slowly pour water against the uphill side of the sugar, taking care not to overflow the downhill end of the tray. Look inside the clay to see the effect of the water. Record your observations. 41 Name Essential Question How Does Water Change Earth’s Surface? Set a Purpose Record Your Data What will you learn from this activity? Use the table below to record your observations. Draw or describe your model’s appearance before and after you pour the water. Top view Think About the Procedure 1. What do the materials in the activity represent? © Houghton Mifflin Harcourt Publishing Company 2. Why do you position the tray to produce a slope? Front view Side view Before water After water 385
What happened to the sugar under the clay? Describe how your model demonstrates a process that shapes landforms. Analyze and Extend 1. What would you expect to happen in places with steeper slopes where water moves downhill faster? 2. What would you expect to happen in places where it rains daily compared to places that receive very little rain? 386 3. What is the role of the clay in this model? What does it represent? 4. What additional factors could affect the rate of cave formation? 5. Explain how you could test the effect of one of the factors you listed in question 4. 6. What other questions do you have about how water weathers rock? © Houghton Mifflin Harcourt Publishing Company Draw Conclusions
How Do Plates Move? Earth’s plates are sections of the crust that move. But it is the mantle beneath the crust that is actually moving, and the plates move with it. You can build a model to represent Earth’s layers and demonstrate plate movement. Materials shoebox scissors paper modeling clay Cut two 8 cm by 25 cm strips of paper. Run each strip through the slit in the box. Leave about 10 cm sticking out through the slit. Fold the strips back on opposite sides of the slit. Inquiry Flipchart page 43 Use the clay to make models of North America and South America. Press your models onto the left strip of paper. Make models of Europe, Asia, and Africa, and press them onto the right strip. 4 Slowly push the strips up through the slit. Observe what happens to the clay models. Record your observations. Turn the shoebox upside down, and cut a 1 cm by 10 cm slit across the bottom. Then at the center of one of the box’s long sides, cut out a hole large enough for your hand. 43 Name Essential Question How Do Plates Move? Set a Purpose What will you model during this activity? Draw your model from two angles and label the parts in each. Think About the Procedure What do the materials in this activity represent? Record Your Data © Houghton Mifflin Harcourt Publishing Company Describe what happens as you push the strips of paper up through the slit in the box. 405
Draw Conclusions What does the rising paper in the model represent? Infer what happens to the continental crust as plates move apart. Analyze and Extend 1. Plates can move toward or slide past each other. Use your model to demonstrate these other plate movements. Draw and describe what happens to the continents. 2. By observing and using models, scientists infer how the continents move. Based on your model, what can you infer about the positions of these four continents millions of years ago? What do you predict will happen to these four continents over the next five million years? 3. If the clay represents the crust and the paper strips represent the mantle, how might this explain how the continents move? 406 © Houghton Mifflin Harcourt Publishing Company 4. What other questions would you like to ask about plate movement?
What Are Properties of Minerals? If minerals look the same to you, then it’s time to take a closer look! In this activity, you will classify some minerals by their properties. CAUTION: Handle the nail carefully. It’s sharp! Test the hardness of each mineral. Try to scratch each one with your fingernail, the steel nail, the penny, and the other mineral samples. Record your observations. (Note: A fingernail has a hardness of 2, a penny has a hardness of 3, and a steel nail has a hardness of 5.) Materials mineral samples streak plate steel nail penny Inquiry Flipchart page 45 Observe each mineral sample. Write a word that best describes each sample’s luster. Use each mineral to draw a line across the streak plate. Record the color of the streak. 2 Classify each mineral sample based on luster, streak, and hardness. 45 Name Essential Question What Are Properties of Minerals? Set a Purpose Think About the Procedure Why is it important to know how to classify things? Name three mineral properties you will be using in this activity. Record Your Data In the table below, record your observations. Beneath the table, describe how you would classify the minerals into groups using one of the properties in the table. © Houghton Mifflin Harcourt Publishing Company Mineral Sample Luster Streak Hardness 425
Draw Conclusions Analyze and Extend Which mineral that you tested is the hardest? Which is the softest? Explain how you know. 1. What are some other ways minerals can be classified? Did you classify your minerals in the same way as other students? Why or why not? 426 3. What other questions would you like to ask about the properties of minerals? © Houghton Mifflin Harcourt Publishing Company How did you classify the mineral samples? 2. Based on your observations, which property or properties do you think are most helpful in identifying a mineral? Explain.
How Can You Model Changes in Rock? Rocks change form in an ongoing cycle. In this activity, you’ll model how rock changes from one type to another. Use the third color of clay to make a layer like the first. Place it over the pellets. Identify and record the type of rock you have just modeled. Explain your observations. Materials 3 colors of modeling clay metric ruler sheet of wax paper 5–10 plastic foam packing pellets dowel 2 books wrapped in plastic wrap Flatten clay of one color into a layer measuring 12 cm x 12 cm x 2 cm. Place the layer on a sheet of wax paper. Using clay of a different color, make 5 to 10 clay pellets, each about 2 cm in diameter. Place the clay pellets and the plastic foam pellets on top of the first layer. Inquiry Flipchart page 48 Use the dowel as a rolling pin to apply pressure to the top of your rock model. Next, use the books at the sides of the model to press the rock into a new shape. 4 Identify the new type of rock you’ve modeled. Explain your observations. 48 Name Essential Question How Can You Model Changes in Rock? Set a Purpose Record Your Observations What will you learn from this activity? Draw the side view of what you made in Steps 1–4. Identify the type of rock you modeled and describe your observations. Think About the Procedure How is a model useful to a student? © Houghton Mifflin Harcourt Publishing Company Why is it important to think about what each step in this procedure models in real life? 445
Draw the type of rock you modeled in Step 5. Identify the type of rock you modeled and describe your observations. Analyze and Extend 1. How might using models help scientists understand the ways rocks form? 2. Explain how you could represent weathering and erosion as part of your model. 3. How does your model represent the rock cycle? Draw Conclusions What force are you modeling when you use the books? 4. What other questions do you have about how rock forms? 446 © Houghton Mifflin Harcourt Publishing Company In order for your model to show how metamorphic rock changes into igneous rock, what could you do?
How Can Scientists Use Fossils? Paleontologists use fossils to help determine the ages of the rock layers they are studying. In this activity, you’ll use symbols to represent fossils and determine the correct age order of a set of model rock layers. Each card represents a layer of rock. Each symbol represents a type of fossil that is found in that layer. You will use the relative ages of the “fossils” to put the “rock layers” in order from oldest to youngest. Look for another card that has one of these oldest fossils. Put this card on the table above the first card. It represents the second-oldest rock layer. Materials 8 index cards Spread out the cards on the table in front of you. The oldest fossils are the and the . Put the card representing the rock layer with the oldest fossils at the bottom. black marker Draw one of these 8 sets of symbols on each of your 8 index cards. Inquiry Flipchart page 52 Order the rest of the cards in the same way, until you have a line of 8 cards that represent rock layers in order from oldest to youngest. 3 Record the fossils in your layers from oldest at the bottom to youngest at the top. 52 Name Essential Question How Can Scientists Use Fossils? Set a Purpose What will you learn from this activity? How would the results change if only one fossil symbol was drawn on each card? Record Your Data State Your Hypothesis Write your hypothesis or testable statement. Record your results in the space below. Sequence of Rock Layers Fossil Symbols (Oldest to Youngest) Youngest Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Why is it important to examine the fossil symbols carefully? Oldest 483
Draw Conclusions Analyze and Extend Use your card stack to identify the fossils from oldest to youngest. Record your sequence here. 1. Scientists use time-space relationships to compare rock layers around the world. What can you tell about the age of the fossil using this information? Fossil Fossil Oldest to Youngest is 25 to 50 million years old. is 75 to 110 million years old. Fossil Symbols Youngest 2. What has most likely occurred if a fossil that appeared in an older rock layer does not appear in a younger rock layer? 3. Suppose fossil # appeared in each rock layer. Would fossil # make a good index fossil? Explain. Oldest Is the fossil $ older or younger than the fossil ? 484 © Houghton Mifflin Harcourt Publishing Company 4. What other questions do you have about how scientists use fossils?
How Can You Model Ocean Water? In this activity, you will model how salinity affects the movement of ocean water. 3 Repeat Step 1, only this time, place the saltwater bottle on top of the freshwater bottle. Remove the card and observe. Materials table salt measuring spoons two 1-L plastic bottles water food coloring plastic tub index card lab apron Dissolve half a teaspoon of salt in one bottle half full of water and add a few drops of food coloring. Then, fill both bottles all the way to the top with water. Work in the plastic tub to catch spilled water. Press an index card over the opening of the bottle with the clear water. Carefully invert it. Place the upside-down bottle of fresh water on top of the salt water so the rims line up. Hold the bottles in place while someone else removes the index card. Observe for several moments. Inquiry Flipchart page 56 Repeat Step 1 again, and this time, hold both bottles together horizontally. Remove the card and observe. Modify the experiment and repeat it. Use warm fresh water and very cold colored salt water the next time around. 56 Name Essential Question How Can We Model Ocean Water? Set a Purpose Record Your Data What will you learn from this experiment? Use the chart below to record your observations. Describe what you see during each observation. Think About the Procedure What are the conditions that you will control and try to make the same for each trial? Starting position of the bottles Behavior of the water Trial 1 Why is it important to repeat the procedure with the bottles in different positions? Trial 2 Trial 3 © Houghton Mifflin Harcourt Publishing Company Trial 4 Trial 5 Trial 6 517
Draw Conclusions Analyze and Extend Which trial produced the fastest results? Draw what you observed. 1. How does this activity relate to currents in the ocean? 2. Overall, how does colder, saltier water behave in the ocean? 3. How does the behavior of colder, saltier water affect warmer, less salty water? Which is more dense: salt water or fresh water? How do you know? How did changing the temperature of the water affect the outcome of the last three trials? 518 © Houghton Mifflin Harcourt Publishing Company 4. What other questions would you like to ask about ocean water?
How Do We Observe Objects in the Solar System? In this activity, you will investigate ways scientists observe and record data about objects in the solar system. You will model different kinds of observations. Have one member of your group walk to the poster and record observations. After a moment, have another student gather those observations and return them to the group. Inquiry Flipchart page 59 Materials poster of solar system objects binoculars Use binoculars to observe the same object. Record your observations. Observe your assigned object from far away. Make as many observations as possible. Record your observations in your Science Notebook. As a group, review the observations and write new questions about the object. Send the questions to the student standing by the object. Review the answers. 2 A Word for the Wise A space probe is a crewless space vehicle used to explore objects in space and send data back to Earth. Name Essential Question How Do We Observe Objects in the Solar System? Set a Purpose Record Your Data What do you think you will learn from this investigation? In the space below, record the observations you made using all three methods. Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Why do you think you will observe the object in different ways? Why is it important that you work together as a team in this investigation? 559
Draw Conclusions Think about how scientists view objects in space. What did observing the object from far away represent? What did using binoculars represent? What did viewing the object up close represent? 2. How did your observations made using binoculars differ from the observations made when a student walked to the poster? Give an example. 3. How do space probes help scientists learn about objects in space? 4. Think about objects in the solar system. How do scientists use time and space relationships to observe them? Analyze and Extend 560 5. Think of other questions you would like to ask about how scientists study objects in space. Write your questions. © Houghton Mifflin Harcourt Publishing Company 1. How did your observations from far away differ from those made using binoculars? Give an example.
How Does Water Change? What happens to ice as it melts? What properties change? What properties stay the same? In this activity, you will measure and observe properties as ice changes to water. Dry the outside of the bag with a paper towel. Use a balance to measure the mass of the bag and ice. Record the mass. Gr. 2 -15 Materials plastic cup balance resealable plastic bag crushed ice paper towels Gr. 2 -15 Place the bag on a paper towel and allow the ice to melt. While you are waiting, explain why the ice melts and predict what will happen to the mass of the ice when it melts. Inquiry Flipchart page 64 Gr. 2 -15 Fill a plastic cup with crushed ice. Pour the ice into a resealable plastic bag. Seal the bag tightly. Gr. 2 -15 When the ice is completely melted, dry the outside of the bag thoroughly with a paper towel. 2 Gr. 2 -15 Measure and record the mass of the bag and water. Compare the mass of the water to the ice. 64 Name Essential Question How Does Water Change? Set a Purpose Record Your Observations What can you learn from this experiment? In the space below, draw a table to record the masses that you measured. Think About the Procedure Why do you dry the bag in step 2? Where did the moisture on the outside of the bag come from? Make a Prediction © Houghton Mifflin Harcourt Publishing Company Write your prediction from step 3. 595
Draw Conclusions Was your prediction correct? Explain. 3. What do you predict would happen to the mass if you put the bag from step 5 in the freezer and then found the mass after the water changed back to ice? 4. Suppose you poured the water from step 5 into a container and measured its volume. If you froze the water, would its volume change or stay the same? Explain. Analyze and Extend 1. Why was the mass of the bag not important in this activity? 596 © Houghton Mifflin Harcourt Publishing Company 2. What properties of water changed during this activity? What properties did not change? 5. What other questions would you like to ask about how water changes during a physical change? What experiments could you do to answer the questions?
What Affects the Speed of Dissolving? Do all substances dissolve quickly? In this activity, you will explore how to speed up the rate at which a solid dissolves in water. Materials safety goggles lab apron cold tap water 3 clear containers measuring spoon table salt stopwatch 2 spoons coarse salt warm water For Steps 2–4, you will use a stopwatch to measure how long it takes for the salt in each container to completely dissolve. Stop timing if the salt has not dissolved after two minutes. Empty and rinse the containers between steps. CAUTION: Wear goggles and an apron. Measure out equal amounts of tap water into three containers. Add a spoonful of table salt to each container. Do not stir one container. Stir one at a moderate rate, and the other at a fast rate. Inquiry Flipchart page 67 Measure out equal amounts of tap water into two containers. Add a spoonful of coarse salt to one container and a spoonful of table salt to the other. Stir both at the same rate. 5 Pour some cold water into a container. Pour an equal amount of warm water into another container. Add a spoonful of table salt to both containers. Stir both at the same rate. 67 Name Essential Question What Affects the Speed of Dissolving? Set a Purpose What will you learn from this experiment? State Your Hypothesis Write your hypothesis, or testable statement. © Houghton Mifflin Harcourt Publishing Company Think About the Procedure Why do you need to rinse the containers between steps? Would it affect the conclusions for this activity if two different groups stirred at different rates? Record Your Data Record your results in the data table below. Time It Takes to Dissolve Treatment Time (sec) No Stirring Stirring Slowly Stirring Quickly Coarse Salt Table Salt Cold Water Warm Water 627
Draw Conclusions Make a bar graph to display the data in which you tested how stirring affects the rate of dissolving. 2. Minerals dissolve in river water. Would you expect minerals to dissolve faster in a fast-moving river or one that moves slowly? Why? 3. A water softener is a device that uses salts to remove certain substances from water. Most home water softeners use salt pellets or rock salt, both of which are chunks of salt. Why wouldn’t you want to use table salt in a softener? What conclusion can you draw? 4. Think of other questions you would like to ask about the rate of dissolving a solid in water. Analyze and Extend 628 © Houghton Mifflin Harcourt Publishing Company 1. You’re adding sugar to a glass of iced tea. How might you speed up how quickly the sugar dissolves?
How Does Sound Travel Through Solids, Liquids, and Gases? Sound can’t travel through space, but it can travel through matter. In this activity, you and a classmate will explore how sound vibrations change as they travel through different types of matter. Have your partner place the drum on a desktop. Press an ear gently on the desktop. Cover your other ear with your hand. Listen as your partner taps the drum. Record your observations. Materials cylindrical container round balloon scissors rubber band unsharpened pencil cardboard tube plastic cup water Press an ear against the wall. Cover your other ear with your hand. Have your partner tap the drum while holding it on the wall. Listen, and record your observations. Work with a partner to construct a drum. Cut the bottom off a round balloon. Tightly stretch the balloon over the opening of your container. Secure the balloon with a rubber band. Have your partner tap the drum you have made with the pencil. Listen, and record your observations. Hold one end of a cardboard tube to an ear. Cover your other ear with your hand. Have your partner hold the drum against the open end of the tube and tap the drum. Listen, and record your observations. Inquiry Flipchart page 70 2 Press the side of a cup to an ear. Cover your other ear with your hand. Have your partner hold the drum to the other side of the cup and tap the drum. Listen, and record your observations. Fill the cup with water, and repeat Step 5. 70 Name Essential Question How Does Sound Travel Through Solids, Liquids, and Gases? Set a Purpose What variable will you change in each trial? What about sound will you understand better after completing this experiment? Think About the Procedure What stays the same in all of the trials? Why will you start by listening to the sound without pressing your ear against any surface? Record Your Data © Houghton Mifflin Harcourt Publishing Company Record your observations in the table below. How do sound waves travel to your ear? Step 1 From the drum through air (gas) Step 2 Step 3 Step 4 Step 5 Step 6 Describe each sound. 665
Draw Conclusions Analyze and Extend Why did you place a hand over your free ear in Steps 2–5? 1. Based on your observations, what statement can you make about how gases, liquids, and solids can change the way we hear a sound? Did the sound change from Step 1 to Step 2? Explain. 2. Why might the results you got differ from those of other groups? Were your descriptions of the sounds in Step 1 and Step 4 different? Why? 3. Most of the sounds you hear travel through air, which is a gas. If you could, how would you change the procedure to better hear sounds transmitted through solids and liquids? Why do you think the sounds produced in Steps 5 and 6 were different? 666 © Houghton Mifflin Harcourt Publishing Company 4. What other questions would you like to ask about how sound travels in different types of matter?
What Happens When Light Is Reflected? In this activity, you will explore how a mirror reﬂects light. Materials piece of corrugated cardboard, 10 cm x 10 cm 3 pushpins of different colors modeling clay small mirror metric ruler protractor labels Position yourself so your eyes are level with the pins. Align yourself so that your view of Pin 1 lines up exactly with the reflection of Pin 2. Push Pin 3 into the cardboard at the edge of the mirror, right in front of the reflection of Pin 2. Pin 1, Pin 3, and the reflection of Pin 2 should appear to be in a straight line, in that order. Draw lines on the cardboard to connect Pin 3 with Pin 1 and Pin 2. These lines show how the light from the reflection of Pin 2 traveled to your eye. Inquiry Flipchart page 74 Lay the cardboard flat. Use clay to stand the mirror vertically at one end of the cardboard. Make tiny labels for the pushpins. Call them Pins 1, 2, and 3. Push Pins 1 and 2 into the cardboard, about 5 cm from the front of the mirror. 5 Draw a line along the front of the mirror. Remove the mirror from the cardboard. Using the protractor, measure the angle between the pushpin lines and the mirror line. Record your results. 74 Name Essential Question What Happens When Light Is Reflected? Set a Purpose What do you expect to understand about light after you complete this investigation? How is the mirror different from all of the other materials in the experiment? What is the same about the positions of the first two pushpins? Write a statement that tells what you plan to investigate. Record Your Data In the space below, record your measurements of the two angles described in Step 4. Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Why do you think it is important to tape the mirror so that it stands up straight? 691
Draw Conclusions Compare the two angles you measured in Step 4. What do they have in common? What do the lines you drew show about the path of light? 2. Suppose you know the angle at which light hits a mirror. Predict the angle at which the light will reflect. 3. Look closely at the word reflection. One of the meanings of the Latin prefix reis “again.” How does this meaning relate to the reflection you observed in the investigation? Analyze and Extend 1. How would a mirror be less useful to people if it did not reflect light in a straight line? 692 © Houghton Mifflin Harcourt Publishing Company 4. What other questions would you like to explore about how light travels when it strikes different surfaces?
How Do Forces Affect Motion? Repeat Step 3 using the 3-cm and 5-cm marks. What can you do to make a toy truck move faster or travel farther? Inquiry Flipchart page 77 Materials ruler safety goggles giant rubber band toy truck meterstick chair metal bolts tape CAUTION: Wear goggles. Cut a rubber band in half, and tie the ends around the legs of a chair. Place a piece of tape on the floor. Mark lines that are 1 cm, 3 cm, and 5 cm behind the rubber band. 2 Place a toy truck against the rubber band. Pull the truck back to the 1-cm mark, and release it. Measure the distance the truck travels, and record the data. Repeat this step two more times. Place four bolts in the toy truck. Launch the truck from the 3-cm mark, and record the distance it travels. Repeat this step two more times. Add four more bolts to the truck. Repeat Step 5. 77 Name Essential Question How Do Forces Affect Motion? Set a Purpose Why do you add bolts to the truck? What will you learn from this experiment? State Your Hypothesis Record Your Data Write your hypothesis, or testable statement. In the table below, record the data you gathered. How Forces Affect Motion Part I: Distance rubber band was stretched 1 cm 3 cm 5 cm Distance traveled (cm) Part II: Empty truck Think About the Procedure © Houghton Mifflin Harcourt Publishing Company Why do you use a rubber band to start the toy truck rather than your hand? Rubber band stretched to 3 cm Truck with 4 bolts Truck with 8 bolts Distance traveled (cm) Trial 1 Distance traveled (cm) Trial 2 Distance traveled (cm) Trial 3 719
Draw Conclusions Analyze and Extend Each time you changed a variable and launched the truck, you ran three trials. Calculate the average distance traveled by the truck in each experimental setting. 1. Interpret your data. How is an object’s mass related to its change in motion when acted on by a force? Experimental settings Rubber band at 1 cm Rubber band at 3 cm Rubber band at 5 cm Average distance traveled (cm) 2. How does the size of the force applied to an object affect its motion? Truck with 0 bolts Truck with 4 bolts Truck with 8 bolts Draw two bar graphs to display your data. 3. Why is it important to repeat an experiment several times or to have several people perform the same experiment? 720 © Houghton Mifflin Harcourt Publishing Company 4. Write another question you could ask about using forces and motion. What experiment could you do to answer your question?
What Are Balanced and Unbalanced Forces? Think about an object that is not moving. What do you need to do to make it move? Does the mass of the object make a difference? Materials spring scale 3 wood blocks with hooks sandpaper waxed paper vegetable oil Inquiry Flipchart page 78 Use the spring scale to lift a block. Observe and record the force needed to overcome the force of gravity. Place one block on its side on a piece of sandpaper. Attach the spring scale, and pull it gently. Record the scale reading just as the block begins to move. Repeat this measurement two more times. Repeat Step 1 with two blocks and then again with three blocks. 3 Repeat Step 3 with the block on other surfaces, such as waxed paper and waxed paper that has been coated with vegetable oil. 78 Name Essential Question What Are Balanced and Unbalanced Forces? Set a Purpose Record Your Data What will you learn from this investigation? Record your measurements in this table. Forces Investigation Action Force (N) Think About the Procedure What forces are acting on the blocks when they are sitting on the table? Lift one block Lift two blocks Lift three blocks Pull block on sandpaper Pull block on waxed paper Pull block on oiled paper Why will you pull the block across several different surfaces? Draw Conclusions © Houghton Mifflin Harcourt Publishing Company What is required to start an object moving? 721
Analyze and Extend 1. The block below is being pulled to the right. Draw arrows to show the forces acting on the object. Label each arrow. 2. At what point during this activity were the forces on the block balanced? Draw the block, and show the forces as arrows. 4. What forces acted on the block as you tried to pull it horizontally? Were the forces balanced or unbalanced? 5. Why did the blocks require a different force to begin moving on the three different surfaces? 6. What other questions would you like to ask about balanced and unbalanced forces? What investigations could you do to answer the questions? 722 © Houghton Mifflin Harcourt Publishing Company 3. How is an object’s mass related to the upward force needed to overcome the pull of gravity?