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Buckle Down North Carolina EOG 8 Science Unit 1 …€¦ · Review 2: Reporting and Analyzing Data. ... Review 11: Interpreting the Earth’s History ... probing the secrets of DNA,

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Page 1: Buckle Down North Carolina EOG 8 Science Unit 1 …€¦ · Review 2: Reporting and Analyzing Data. ... Review 11: Interpreting the Earth’s History ... probing the secrets of DNA,

EOG

P.O. Box 2180Iowa City, Iowa 52244-2180

PHONE: 800-776-3454FAX: 877-365-0111

www.BuckleDown.com

Student Set NC02098S1Includes: Student Workbook, Form A Practice Test, Form B Practice Test

Individual Products:Student Workbook NC02098W1Form A Practice Test NC02098A1Form B Practice Test NC02098B1

8

Buckle Down North Carolina EOG 8 Science

Unit 1 Scientific Inquiry

Review 1: Scientific Investigations Review 2: Reporting and Analyzing Data

Unit 2 Understanding Technology

Review 3: Science and Technology Review 4: Process of Engineering Design

Unit 3 Physical Science

Review 5: Physical Properties of Matter Review 6: Chemical Properties of Matter Review 7: Properties of Water

Unit 4 Life Science

Review 8: Cellular Biology Review 9: Microbes, Chemicals, and Disease Review 10: Evolution and Natural Selection

Unit 5 Earth Science

Review 11: Interpreting the Earth’s History Review 12: Studying the Earth’s Surface Review 13: The Hydrosphere

Go to www.BuckleDown.com to review our complete line of EOG and EOC materials for Grades 3–12 READING • WRITING • MATHEMATICS • SCIENCE

North Carolina

8 S

CIE

NC

E

The cover image depicts a vortex, which is fluid whirling about a central axis. Some examples of vortices in nature include tornadoes, hurricanes, and whirlpools.

North C

arolina EO

G

Science

9 7 8 0 7 8 3 6 5 3 1 9 8

ISBN 0-7836-5319-051495

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.TABLE OF CONTENTS

Introduction .................................................................................. 1

Tips for Taking Science Tests ............................................. 1

Unit 1 – Scientific Inquiry ............................................................ 3

Review 1: Scientific Investigations .................................... 4Content Objectives: 1.01–1.05, 1.08

Review 2: Reporting and Analyzing Data ........................ 18Content Objectives: 1.01–1.09

Unit 2 – Understanding Technology ......................................... 35

Review 3: Science and Technology ................................... 36Content Objectives: 1.10, 2.01–2.02, 4.10, 7.05

Review 4: Process of Engineering Design ........................ 51Content Objectives: 2.03–2.04

Unit 3 – Physical Science ............................................................ 61

Review 5: Physical Properties of Matter ......................... 62Content Objectives: 4.04–4.06

Review 6: Chemical Properties of Matter ........................ 73Content Objectives: 4.01–4.07

Review 7: Properties of Water .......................................... 86Content Objective: 3.01

Unit 4 – Life Science .................................................................... 97

Review 8: Cellular Biology ............................................... 98Content Objectives: 6.01–6.04

Review 9: Microbes, Chemicals, and Disease ................ 112Content Objectives: 4.08–4.10, 7.01–7.04

Review 10: Evolution and Natural Selection ................ 126 Content Objectives: 5.01–5.02

Unit 5 – Earth Science ............................................................... 139

Review 11: Interpreting the Earth’s History ................. 140 Content Objectives: 5.01–5.03

Review 12: Studying the Earth’s Surface ...................... 158 Content Objectives: 5.03–5.05

Review 13: The Hydrosphere ......................................... 173 Content Objectives: 3.02–3.08

Glossary ......................................................................................... 191

iii

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Table of Contents

To the Teacher:

“Content Objective” codes are listed for each review in the table of contents and for each page in the shaded gray bars that run across the tops of the pages in the workbook (see example to the right). These codes indicate which Content Objectives are covered in a given review or on a given page.

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Review 1

Scientific InvestigationsThink about all the kinds of scientific research you’ve heard about: Geneticists probing the secrets of DNA, marine biologists tracking whales across oceans, and cosmologists considering the beginning of the universe. These pursuits have a common goal—to discover and explain the patterns at work in natural systems. Scientists develop theories that explain their observations and predict events not yet witnessed. As scientists gather more evidence, however, scientific theories can change. But scientists need specific mental skills to interpret the evidence that they gather. Scientists also need to know how to design and carry out a systematic investigation to gather data they can trust. This review will take you through the steps of designing and performing a systematic investigation.

Scientific SkillsIn science, a description is an account of an event or a process. An explanation tells why or how that event or process happened, and says why that event or process is important. A good explanation can also be used to make a prediction, or a statement about what may happen given specific conditions.

David sees smoke rising from behind Susan’s house. He calls Susan and exclaims, “Hey! There’s smoke coming up from behind your house!” Susan responds, “Relax. We’re grilling some steaks in the backyard.”

In this exchange, who made a description and who gave an explanation?

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Content Objectives: 1.05

explanationfair testhypothesisindependent

variableinferenceobservation

WordstoKnow

conclusionconstantcontrol groupcontrolled

variabledependent

variabledescription

predictionresearch

questionsample sizesystematic

investigationvariable

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When scientists explain their observations, they sometimes make inferences. An inference is a conclusion that compares our observations with what we think to be true. Inferences are based on limited observations and knowledge, so they are sometimes called “educated guesses.”

After David saw the smoke, what inference did he probably make?

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Observing, describing, explaining, predicting, and inferring are basic skills that scientists use when making and testing a hypothesis. A hypothesis is a statement that can be tested, either by experiment or observation, about some event or process. A hypothesis may also make a prediction: “If a certain event X happens, then event Y will happen as a response.” Many scientists will run experiments and collect data to test the hypothesis. If the hypothesis stands up to repeated testing, explains a wide range of data, and makes successful predictions, then it may become more than a hypothesis—it may become a theory.

Consider this statement: “An amount of water at 50° C will be able to dissolve more sugar than the same amount of water at 20° C.” Explain why this statement is a hypothesis.

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Now that we’ve reviewed some of the basic vocabulary of gathering and interpreting data, let’s turn to the nuts and bolts of experimentation: designing and carrying out a systematic investigation.

Content Objectives: 1.05

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First FlightsJuanita has built a balsa wood glider with a 1 m wingspan. The glider does not fly as far as she would like, so she needs to make some changes. She has many choices for changes. She could shorten the wings, or add weight along some part of the body, or lengthen the tail, and so on. How can she keep track of which changes make her glider fly better and which do not? In this situation, a systematic investigation can be very helpful.

To start her investigation, Juanita takes her glider to her school’s gym and makes 10 test flights. She wants to know the lengths of the shortest and longest flights.

Name two things Juanita must do to know the distances of the shortest and longest flights.

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Juanita considers shortening the wings, adding weight near the nose, and lengthening the tail—all at the same time. After some thinking, she realizes that this is not the best way to figure out how to improve her glider.

Why do you think Juanita decided that this was not the best way to figure out how to improve her glider?

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Content Objectives: 1.01, 1.02, 1.0�, 1.05

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Elements of a Systematic InvestigationJuanita may not realize it, but she is thinking like a scientist. She has a research question, or a question that she wants to explore: How can I get my glider to fly farther? She has a hypothesis, or a testable idea: Changing one or more parts of my glider may get it to fly farther. Finally, she knows that she has to test one variable, or changeable factor, at a time. Changing three variables at once (wingspan, weight, and tail length) would make it impossible to figure out how each variable individually affects the glider’s flight.

If you were Juanita, which of the three variables would you test first? Why?

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Types of VariablesAny systematic investigation has three types of variables. The independent variable is the single factor that the investigator will change with each trial. The dependent variable is the factor that may or may not be affected by the change to the independent variable. The controlled variables are all of the other factors that the investigator will try to keep exactly the same with each trial. In the case of Juanita’s glider, many factors can affect the glider’s flight—the strength of the throw, the direction and speed of the wind, and so on. When Juanita does her trials, she must try to keep such factors as constant as possible. Otherwise, she will not be sure whether the changes to the independent variable are causing her results, or whether other, outside factors are responsible. Because controlled variables should be kept the same from trial to trial, scientists call them constants.

Suggest how Juanita can keep factors such as the speed and direction of the wind constant in her trials.

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Content Objectives: 1.01, 1.02, 1.0�, 1.05

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A fair test makes a change in just one independent variable at a time, to see how the change affects the dependent variable. Ideally, only one independent variable should be tested at a time.

Why might it be difficult to test just one independent variable at a time? Use the example of Juanita and her glider in your answer.

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Juanita’s study also needs a control group—a set of observations in which no variables are changed. By comparing the results from the control group with the results from an experimental group, Juanita can figure out how her changes are affecting the glider’s flight.

Juanita already has a control group. (You read about it earlier.) What is it?

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Juanita chooses her independent variable. She will change the weight along the body of the glider. She will put a 25 g clip at one spot along the bottom and throw the glider five times. Then, she will move the clip to a different spot on the body and throw the glider five more times.

Juanita’s hypothesis (her testable idea) is now more focused. Restate it.

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What is Juanita’s independent variable?

_____________________________________________________________________________________________________________________________________________

What is Juanita’s dependent variable?

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Content Objectives: 1.01, 1.02, 1.0�, 1.05

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Sample SizeWhen conducting an experiment or making an observation, scientists must consider the sample size. The sample size is the number of observations made when gathering the data. Scientists cannot draw accurate conclusions by making just one observation or doing just one trial. The more observations they get or trials they do, the more accurate their conclusions will be.

Juanita’s friend Charelle says that Juanita is working too hard. Charelle says that each time Juanita moves the clip, she should throw the glider only once. Will this method produce a sufficient sample size? Explain your answer.

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Drawing ConclusionsAfter Juanita performs all of her trials, she examines her data and reaches the following conclusion: Placing the 25 g clip a distance of 4 cm behind the glider’s nose makes it fly the farthest.

Does this conclusion mean that Juanita’s investigation is done? Possibly. But maybe Juanita wants to see if she can make her glider fly even farther. If so, then her conclusion can become a new hypothesis.

Juanita’s new hypothesis is, “Putting a 25 g mass at 4 cm behind the nose makes the glider fly the farthest.” Suggest an experiment that could test this claim.

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Content Objectives: 1.01, 1.02, 1.0�, 1.05, 1.0�

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Safety RulesExperienced scientists practice general safety rules whenever they are in the scientific laboratory, no matter how safe an experiment seems. During every investigation, you should follow the safety standards listed in the following table. Doing so will help make your lab experience much more fun and educational.

General Science Safety Rules

Content Objectives: 1.0�

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Additionally, you should make sure that your laboratory has adequate ventilation. Many chemicals can give off toxic fumes, and you won’t always be able to sense them before they damage your health.

Why is it important never to return chemicals used in an experiment to their original containers?

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Keys to Keep Scientists observe, describe, explain, predict, and make inferences

about events in the natural world.

A hypothesis is a statement that can be tested by experimentation or observation.

Scientists use systematic investigations to investigate the natural world.

A systematic investigation includes an independent variable, a dependent variable, and constants.

Experiments must have appropriate sample sizes and control groups.

Always evaluate the safety issues before starting a scientific investigation.

Content Objectives: 1.0�

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Explore It Yourself

In this activity, you will design an experiment to study the effect that the temperature of water has on water’s ability to dissolve sugar. A classmate will then evaluate the design of your experiment.

As you design your experiment, imagine that you have the following equipment:

• one 250-mL beaker • a thermometer

• a large supply of granulated sugar • a stopwatch

• a balance (digital or mechanical) • a small scoop

• cold water, room-temperature water, • a stirring rod and hot water

Note: There are different ways to test the relationship between water, temperature, and dissolving sugar, so the experiment you design may differ from your classmates’ experiments.

Step 1: Write a hypothesis that your experiment will test.

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Step 2: Identify the independent variable. This is the variable that you will change and that may cause an observable effect in the dependent variable.

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Step 3: Identify the dependent variable. This is the variable that you observe, to see how or whether it changes in response to a change in the independent variable.

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Step 4: Identify two variables to control. These are factors that must be kept constant throughout your experiment.

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Content Objectives: 1.01–1.05

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Step 5: Suggest uses for the following tools in your experiment.

Thermometer: _________________________________________________________________________________

Stopwatch: _____________________________________________________________________________________

Stirring rod: ___________________________________________________________________________________

Step 6: Use your answers from Steps 1 through 5 to write your experimental procedure. Be as clear and as detailed as possible with the steps of your procedure, numbering them where necessary. Also describe how you will record the data that you get.

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Content Objectives: 1.01–1.05

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What Does It Mean?Directions: Exchange your workbook with a classmate. Write your name in your classmate’s workbook, so that your classmate will remember who wrote in his or her book and can ask you questions later. Read everything that he or she wrote in the “Explore It Yourself” section. Then respond to the following questions.

Name of student evaluating procedure: ______________________________________________________________________

1. Was your classmate’s experimental design different than yours? If so, explain how.

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2. Can your classmate’s hypothesis be tested by a scientific procedure? If not, explain why not.

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3. When a scientist designs an experiment, he or she must make instructions that are clear enough so that any other scientist can perform the experiment.

Identify two places where your classmate’s instructions were especially clear.

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Give your classmate one suggestion for improving the instructions of his or her experimental procedure.

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Content Objectives: 1.01–1.05

The following page starts the EOG Science Practice section.

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EOG Science Practice

15

GO ON

1. A student designed an experiment to study how temperature affects the rate at which an enzyme digests a protein. She put equal masses of liver into four equal-sized test tubes, brought the test tubes to different temperatures, introduced equal amounts of enzyme to each tube, and measured the duration of the chemical reaction.

What factors were held constant in the student’s experiment?

A liver mass, test tube size, and enzyme amount

B liver mass, enzyme amount, and reaction duration

C test tube temperature and reaction duration

D test tube temperature, liver mass, and enzyme amount

2. Scientists say that the Sun appears to move in the sky because the Earth is rotating on its axis. What is this an example of?

A a description

B an explanation

C an inference

D a prediction

3. A student wanted to know whether a new brand of shoe could make a basketball player jump higher. He found 18 basketball players who started using the shoes this season and measured how high each player could jump in the new shoes.

What error did the student make in his investigation?

A He did not clearly state his research question.

B There was no control group for the study.

C The sample size was much too small.

D The student was biased in favor of the new shoe.

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EOG Science Practice

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4. A student hypothesized that robins prefer large birdhouses to small ones. He built four birdhouses of different sizes to test his hypothesis. What was the independent variable in the student’s study?

A the size of the birdhouse

B the number of birds in a house

C the location of the birdhouse

D the season of the year

5. A student designed an experiment to test the following hypothesis: The mass of a pendulum bob does not affect how long it takes the pendulum to make one complete swing. Four steps of the activity are listed below, but not in the correct order.

1. Find the masses of four different bobs.

2. Construct a table in which to record data.

3. Time the duration of one swing.

4. Tie the four bobs to four strings of equal length.

In which order should the student conduct these steps?

A 1–2–4–3

B 2–4–3–1

C 4–2–1–3

D 2–1–4–3

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EOG Science Practice

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6. A student experimented with how long it took different amounts of water to boil. She boiled 100, 200, 400, 800, and 1,600 g of water in the same pot. Between each trial, she let the pot and the burner cool to room temperature.

What was the independent variable in the student’s study?

A the size of the pot

B the time needed to boil

C the temperature of the room

D the mass of the water

7. Which of the following safety procedures must always be practiced in the laboratory?

A Never eat or drink in the laboratory.

B Heat liquids only in open containers.

C Never touch, taste, or smell unknown chemicals.

D All of the above procedures must always be practiced.

8. A student wants to find out whether the baseballs used in his league fly farther than the baseballs used the year before. He has noticed that many more home runs have been hit this year than last year, so he thinks the new balls have more bounce. The student wants to design an experiment to test this idea.

What is the student’s hypothesis?

A Many more home runs have been hit this year than last year.

B The balls are flying farther this year than last year.

C The new balls used by the baseball league have more bounce.

D An experiment will test whether the baseballs fly farther.

STOP

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