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35406 ISBN-10: 0-7891-8232-7

ISBN-13: 978-0-7891-8232-6

Printed in the United States of America

Science

Grade 8

Texas

Essential Knowledge and Skills

ReviewersVanessa Contrares • Rayford Intermediate School • Aldine Independent School DistrictKarri Dawes • Pearson Elementary School • Garland Independent School DistrictElizabeth Donovan • Griffin Middle School • Frisco Independent School DistrictStarlette Gerik • T. A. Howard Middle School • Mansfield Independent School DistrictLaura Grannell • Rodriguez Elementary School • Austin Independent School DistrictCatha Ivy • Colony Meadows Elementary • Fort Bend Independent School DistrictToni Jones • Scobee Middle School • Southwest Independent School DistrictLinda Lyles • Larry G. Smith Elementary • Dallas Independent School DistrictLynda Marazzini • Elma Neal Elementary • San Antonio Independent School DistrictMaria Moreno • Rico Elementary • Weslaco Independent School DistrictSonia Rodas • Hedrick Elementary • Lewisville Independent School District Antoinette Syler • Pearland Junior High East • Pearland Independent School DistrictMarti Turner • Waco ISD Curriculum Department • Waco Independent School DistrictIeshia Webb • Alief Learning Center • Alief Independent School District

2 To the Student © Perfection Learning® No reproduction permitted.

To the StudentSoon you will be taking assessments of academic readiness for science. This Better

Test Scores book will give you the practice and confidence you need to do well on this important test. Here are the steps to follow to use this book.

1. Take Tryout Test 1 and check your answers. Use the chart at the bottom of this page to find out your strengths and weaknesses in the science areas assessed. Don’t be discouraged if you don’t get all of the answers right or if you don’t understand some questions. Remember the hard questions. They will be the types of questions you need to work on the most.

2. Work through the lessons that follow Tryout Test 1. These lessons will help you with the kinds of questions you will be asked on the assessments of academic readiness for science. Each lesson ends with a short practice test to reinforce your new skills. Fill in the Keeping Score chart on page 85 as you complete each practice test.

3. After completing all 7 lessons, take Tryout Test 2. Your score on this test will show how much your test-taking skills have improved.

By following the steps outlined above, you will learn many of the skills you need to do well on the assessments of academic readiness in science.

Lesson Tryout Test 1 Tryout Test 2

1 Matter and Energy I (Reporting Category 1)

1, 2, *5, *6, 7, 8, 10 *2, 3, *4, *5, 8, *9, 12

2 Matter and Energy II (Reporting Category 1)

3, 4, 9, *11, *12, *13, *14 *1, *6, 7, *10, *11, 13, 14

3 Force, Motion, and Energy (Reporting Category 2)

*15, *16, *17, 18, *19, *20, *21, 22, 23, *24, *25, *26

*15, 16, 17, *18, *19, *20, *21, *22, *23, *24, *25, *26

4 Earth and Space I (Reporting Category 3)

27, 28, *29, 30, *31, 32, 33, 34

*27, 28, 29, 30, *31, 32, 33, *34

5 Earth and Space II (Reporting Category 3)

*35, 36, *37, 38, 39, *40 35, *36, 37, *38, 39, *40

6 Organisms and Environments I (Reporting Category 4)

*41, 42, *43, 44, 45, *46, *47, 49, *54

*41, 42, *43, 44, *45, *46, *47, *53, 54

7 Organisms and Environments II (Reporting Category 4)

*48, *50, 51, 52, *53 48, 49, 50, *51, 52

© Perfection Learning® No reproduction permitted. Table of Contents 3

Table of ContentsGrade

SCIENCE

To the Student . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

LESSONS AND TESTS

Tryout Test 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Take this sample test to find out what you know and don’t know.

Reporting Category 1: Matter and Energy

Lesson 1: Matter and Energy I [TEKS: 8.5(A), 8.5(B), 8.5(C), 8.5(D), 8.5(E), 8.5(F), 7.5(C), 7.6(A), 7.6(B), 6.5(C), 6.6(A), 6.6(B)]Describe the structure of atoms, including the masses, electrical charges, and locations, of protons and neutrons in the nucleus and electrons in the electron cloud; identify that protons determine an element’s identity and valence electrons determine its chemical properties, including reactivity; interpret the arrangement of the Periodic Table, including groups and periods, to explain how properties are used to classify elements. Differentiate between elements and compounds on the most basic level. Compare metals, nonmetals, and metalloids using physical properties such as luster, conductivity, or malleability; and calculate density to identify an unknown substance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Lesson 2: Matter and Energy II [TEKS: 8.5(A), 8.5(B), 8.5(C), 8.5(D), 8.5(E), 8.5(F), 7.5(C), 7.6(A), 7.6(B), 6.5(C), 6.6(A), 6.6(B)]Recognize that chemical formulas are used to identify substances and determine the number of atoms of each element in chemical formulas containing subscripts; investigate how evidence of chemical reactions indicate that new substances with different properties are formed; and recognize whether a chemical equation containing coefficients is balanced or not and how that relates to the law of conservation of mass. Diagram the flow of energy through living systems, including food chains, food webs, and energy pyramids; identify that organic compounds contain carbon and other elements such as hydrogen, oxygen, phosphorus, nitrogen, or sulfur; and distinguish between physical and chemical changes in matter in the digestive system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

continued

4 Table of Contents © Perfection Learning® No reproduction permitted.

Reporting Category 2: Force, Motion, and Energy

Lesson 3: Force, Motion, and Energy [TEKS: 8.6(A), 8.6(B), 8.6(C), 7.7(A), 6.8(A), 6.8(C), 6.8(D), 6.9(C)]Demonstrate and calculate how unbalanced forces change the speed or direction of an object’s motion; differentiate between speed, velocity, and acceleration; and investigate and describe applications of Newton’s law of inertia, law of force and acceleration, and law of action-reaction such as in vehicle restraints, sports activities, amusement park rides, Earth’s tectonic activities, and rocket launches. Contrast situations where work is done with different amounts of force to situations where no work is done such as moving a box with a ramp and without a ramp, or standing still. Compare and contrast potential and kinetic energy; calculate average speed using distance and time measurements; and measure and graph changes in motion. Demonstrate energy transformations such as energy in a flashlight battery changes from chemical energy to electrical energy to light energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Reporting Category 3: Earth and Space

Lesson 4: Earth and Space I [TEKS: 8.7(A), 8.7(B), 8.7(C), 8.8(A), 8.8(B), 8.8(C), 8.8(D), 6.11(B)]Model and illustrate how the tilted Earth rotates on its axis, causing day and night, and revolves around the Sun causing changes in seasons; demonstrate and predict the sequence of events in the lunar cycle; and relate the position of the Moon and Sun to their effect on ocean tides. Describe components of the universe, including stars, nebulae, and galaxies, and use models such as the Hertzsprung-Russell diagram for classification; recognize that the Sun is a medium-sized star near the edge of a disc-shaped galaxy of stars and that the Sun is many thousands of times closer to Earth than any other star; explore how different wavelengths of the electromagnetic spectrum such as light and radio waves are used to gain information about distances and properties of components in the universe; and model and describe how light years are used to measure distances and sizes in the universe. Understand that gravity is the force that governs the motion of our solar system. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Lesson 5: Earth and Space II [TEKS: 8.9(A), 8.9(B), 8.9(C), 8.10(A), 8.10(B), 8.10(C), 7.8(C)]Describe the historical development of evidence that supports plate tectonic theory; relate plate tectonics to the formation of crustal features; and interpret topographic maps and satellite views to identify land and erosional features and predict how these features may be reshaped by weathering. Recognize that the Sun provides the energy that drives convection within the atmosphere and oceans, producing winds and ocean currents; identify how global patterns of atmospheric movement influence local weather using weather maps that show high and low pressures and fronts; and identify the role of the oceans in the formation of weather systems such as hurricanes. Model the effects of human activity on groundwater and surface water in a watershed. . . . . . . . . . . . . . . . . 47

LESSONS AND TESTS continued

© Perfection Learning® No reproduction permitted. Table of Contents 5

Reporting Category 4: Organisms and Environments

Lesson 6: Organisms and Environments I [TEKS: 8.11(A), 8.11(B), 8.11(C), 8.11(D), 7.10(B), 7.10(C)] Describe producer/consumer, predator/prey, and parasite/host relationships as they occur in food webs within marine, freshwater, and terrestrial ecosystems; investigate how organisms and populations in an ecosystem depend on and may compete for biotic and abiotic factors such as quantity of light, water, range of temperatures, or soil composition; explore how short- and long-term environmental changes affect organisms and traits in subsequent populations; and recognize human dependence on ocean systems and explain how human activities such as runoff, artificial reefs, or use of resources have modified these systems. Describe how biodiversity contributes to the sustainability of an ecosystem; and observe, record, and describe the role of ecological succession such as in a microhabitat of a garden with weeds. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54

Lesson 7: Organisms and Environments II [TEKS: 7.11(A), 7.11(C), 7.12(B), 7.12(D), 7.12(F), 7.14(B), 7.14(C), 6.12 (D)]Examine organisms or their structures such as insects or leaves and use dichotomous keys for identification; and identify some changes in genetic traits that have occurred over several generations through natural selection and selective breeding such as the Galapagos Medium Ground Finch (Geospiza fortis) or domestic animals. Identify the main functions of the systems of the human organism, including the circulatory, respiratory, skeletal, muscular, digestive, excretory, reproductive, integumentary, nervous, and endocrine systems; differentiate between structure and function in plant and animal cell organelles, including cell membrane, cell wall, nucleus, cytoplasm, mitochondrion, chloroplast, and vacuole; and recognize that according to cell theory all organisms are composed of cells and cells carry on similar functions such as extracting energy from food to sustain life. Compare the results of uniform or diverse offspring from sexual reproduction or asexual reproduction; and recognize that inherited traits of individuals are governed in the genetic material found in the genes within chromosomes in the nucleus. Identify the basic characteristics of organisms, including prokaryotic or eukaryotic, unicellular or multicellular, autotrophic or heterotrophic, and mode of reproduction, that further classify them in the currently recognized Kingdoms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Tryout Test 2 Take this sample test to find out what you’ve learned. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Keeping Score . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Finding Percent . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

LESSONS AND TESTS continued

20 Matter and Energy I © Perfection Learning® No reproduction permitted.

The assessments for science will ask you to . . . • describe the structure of atoms;• identify that protons determine an element’s identity and valence electrons determine its chemical properties, including reactivity;• interpret the arrangement of the Periodic Table to explain how properties are used to classify elements;• differentiate between elements and compounds on the most basic level;• compare metals, nonmetals, and metalloids using physical properties such as luster, conductivity, or malleability; and• calculate density to identify an unknown substance.

Matter and Energy ILesson Lesson Lesson Lesson

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S C I E N C E S C I E N C E S C I E N C E

S C I E N C ES C I E N C ES C I E N C E

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S C I E N C E S C I E N C E S C I E N C E S C I E N C E

S C I E N C ES C I E N C E

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S C I E N C E S C I E N C E S C I E N C E S C I E N C E

S C I E N C E S C I E N C E

Directions: Read each question and choose the best answer. Then mark the letter for the answer you have chosen.

1 On the periodic table below, the highlighted set of elements is called a—

A family. B period. C formula. D complex compound.

© Perfection Learning® No reproduction permitted. Matter and Energy I 21

Example 1 asks you to identify a grouping of elements on the periodic table. Elements are grouped horizontally into periods according to their atomic number. But the illustration highlights a column, so choice B is incorrect. Elements in the periodic table are grouped vertically as families or groups according to the physical or chemical properties that they share. Choice A is the correct answer. Choices C and D list other ways that elements can be described or interact that are not directly related to the periodic table.

Make sure to familiarize yourself with the periodic table. Most of the elements in the table are metals. They are called transitional elements. Elements in the top right corner of the table (including carbon, phosphorus, selenium, iodine, astatine, radon, and the elements to the right and above them, plus hydrogen) are all nonmetals. The elements between the metals and nonmetals (boron, silicon, germanium, arsenic, antimony, and tellurium) are metalloids. Metalloids share properties with both metals and nonmetals. As elements go from left to right along the table, they increase in atomic mass. The horizontal rows are called periods. Elements that share similar properties are placed in the same vertical column, or group.

22 Matter and Energy I © Perfection Learning® No reproduction permitted.

2 The illustration below shows a model of a carbon atom. What particles are represented by the cloud that surrounds the central mass?

F atoms G electrons H neutrons J protons

3 The carbon atom shown in question 2 has six protons, six neutrons, and six electrons. What is its atomic number?

A 6 B 12 C 18 D 36

4 Chromium is a(n)—

F compound. G element. H formula. J reaction.

Example 2 asks you to examine a model of an atom and tell which atomic particles are represented by the cloud that surrounds the center, or nucleus. Choice H, neutrons, and choice J, protons, are both incorrect because neutrons and protons are both located within the nucleus. Choice F is incorrect because the entire model is of an atom. Choice G, electrons, is the correct answer. Electrons orbit the nucleus of an atom.

© Perfection Learning® No reproduction permitted. Matter and Energy I 23

Remember . . .To help remember the difference between elements

and compounds, relate compound words to chemical

compounds. Just as a compound word is made up of

more than one part, a chemical compound is made up

of more than one element.

Test-Taking Tips1 Be familiar with the periodic table. Practice finding elements and determining the characteristics each element has according to its position on the table. Know where the metals, nonmetals, and metalloids are, as well as the characteristics that the elements in key groups share.2 Review the parts of the atom and their charges. Be familiar with how the numbers of protons, neutrons, and electrons change the atomic mass and charge of an atom.

HintDon’t confuse atomic number with atomic mass.Atomic number 5 number of protons in an atomAtomic mass 5 number of protons 1 number of neutrons in an atom

A typical atom is shown below. The electrons orbit the nucleus and have a negative charge. The protons and neutrons are found in the nucleus. Protons have a positive charge, and neutrons have no charge.

In Example 3, you are asked to identify the atomic number of the atom shown. The atomic number is equal to the number of protons in the atom. The correct answer is 6, choice A.

In Example 4, you are given the name of a substance and asked to determine if it is a compound, an element, a formula, or a reaction. Chromium is a simple element; choice G is correct. Choice F, compound, is a chemical combination of two or more elements. Formula, choice H, is the relative number of atoms of each element in a compound. Choice J, reaction, is the process that occurs when two or more substances interact, undergoing a chemical change.

Go for it!

24 © Perfection Learning® No reproduction permitted.

Test Practice 1

Test Practice 1: Matter and Energy I Estimated time: 15 minutes

Directions: Read each question and choose the best answer. Then mark the letter for the answer you have chosen.

1 Chlorine is added to some alcohol chemicals to make weed-killer. Some environmentalists have concerns about the pollution it causes. Using the periodic table, which chemical would you suspect might have similar properties and could possibly be substituted for chlorine?

A magnesium B carbon C chromium D bromine

2 Based on the periodic table shown above, which of the following elements has the largest number of electrons in each atom?

F molybdenum G rhenium H technetium J tungsten

3 Elements that are grouped between metals and nonmetals are called—

A reactants. B gases. C metalloids. D synthetics.

© Perfection Learning® No reproduction permitted. 25

4 Which characteristic below is true of nonmetals?

F They are opaque. G They are good conductors of electricity. H They have a high luster. J They are very brittle.

5 Which set of numbers correctly balances the equation using the smallest units possible?

H2O2 H2O 1 O2

A 1, 2, 1 B 2, 1, 2 C 1, 1, 2 D 2, 2, 1

6 Which of the following equations is NOT balanced?

F C2H61O2 CO21H2O G AgNO3 1 NaI AgI 1 NaNO3

H Ca1Cl2 CaCl2

J 2Fe 1 3Cl2 2FeCl3

7 The difference between carbon-12 and carbon-13 atoms is the—

A number of electrons. B number of neutrons. C number of protons. D charge of the atoms.

8 In a lithium atom (atomic number 3), where are electrons most likely to be located?

F one electron near the nucleus and two electrons farther out G two electrons near the nucleus and one electron farther out H three electrons equidistant from the nucleus J eight electrons, all at different distances from the nucleus

Test Practice 1

26 © Perfection Learning® No reproduction permitted.

Test Practice 1

9 What charge does a neutron particle carry?

A negative B positive C both positive and negative D no charge

10 A neutral atom of copper has 29 protons and 34 neutrons. How many electrons does it have? Record your answer and fill in the bubbles on the grid.

.

0 0 0 0 0 0

1 1 1 1 1 1

2 2 2 2 2 2

3 3 3 3 3 3

4 4 4 4 4 4

5 5 5 5 5 5

6 6 6 6 6 6

7 7 7 7 7 7

8 8 8 8 8 8

9 9 9 9 9 9

11 Examine the model of a radon atom shown below. What is its atomic mass?

F 43 G 86 H 172 J 258

12 Water has a density of 1.0 g/cm3. Substances that are denser than water sink when placed in water. Substances less dense than water float when placed in water. Which of the substances shown in the table float in water?

Densities of Several Common Substances

Substance Density

diamond 3.5 gcm3

cork 0.34 gcm3

ice 0.92 gcm3

olive oil 0.9 gcm3

oak 0.7 gcm3

A diamond only B cork only C cork, ice, olive oil, and oak D They all float.

Points Earned ⁄ Total = ______ ⁄ 12