grade 8 florida science - · pdf fileflorida student handbook fl34 grade 8 florida science...
TRANSCRIPT
FL7
The Nature of Science 2
Science is an ongoing process. 5CHAPTER INVESTIGATION Polymers 12
Scientists use tools to analyze and communicate. 14MATH IN SCIENCE Making Stem-and-Leaf Plots 22
Science and technology are interrelated. 23EXTREME SCIENCE Stronger Than Steel 31
Catching a Draft: The Physics of Stock Car Racing 42
Plant Medicines from Florida 216
Listening to Dolphins 328
Loggerhead Turtles 476
Florida’s Keys and Barrier Islands 638
Student Resources
Florida Resources 817Florida Content Preview 819FCAT Science Reference 830Appendix 831
Student Resource Handbooks R1Scientific Thinking Handbook R2Lab Handbook R10Math Handbook R36Note-Taking Handbook R45
Glossary R52Index R76Acknowledgments R119
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Introducing Science FL26
Unifying Principles of Science FL28Florida Student Handbook FL34
GRADE 8
Florida Science
Sunshine State Standards
42 U it 1 M ti d F
Sunshine State Standards
In “Catching a Draft” you’ll learn about somecommon contact forces. (SC.C.2.3.2)
You’ll also see how an object in motion will continue in a straight line until acted upon by a force. (SC.C.2.3.5)
FLORIDA CONNECTIONS
Motion 46
An object in motion changes position. 49SCIENCE ON THE JOB Physics for Rescuers 55
Speed measures how fast position changes. 56MATH IN SCIENCE Working with Units 64
Acceleration measures how fast velocity changes. 65CHAPTER INVESTIGATION Acceleration and Slope 72
Forces 78
Forces change motion. 81THINK SCIENCE Why Do These Rocks Slide? 88
Force and mass determine acceleration. 89MATH IN SCIENCE Using Significant Figures 96
Forces act in pairs. 97CHAPTER INVESTIGATION Newton’s Laws of Motion 102
Forces transfer momentum. 1044
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Motion and Forces
What must happenfor a team to win thistug of war? page 78
The motion of an object can be described and
predicted.
Forces change the motion of objects in
predictable ways.
FL8 McDougal Littell Science Grade 8
UNIT 1
Unit Features
FRONTIERS IN SCIENCE Robots on Mars 38
FLORIDA CONNECTION Catching a Draft: The Physics of Stock 42Car Racing
TIMELINES IN SCIENCE Understanding Forces 178
Table of Contents FL9
Visual Highlights
Newton’s laws apply to all forces.
Distance-Time Graph 61Velocity-Time Graphs 70Newton’s Three Laws of Motion 100Orbits 121Conserving Mechanical Energy 163Insulation 202
What forces are actingon this snowboarder? on the snow? page 114
Gravity, Friction, and Pressure 114
Gravity is a force exerted by masses. 117EXTREME SCIENCE Bending Light 124
Friction is a force that opposes motion. 125MATH IN SCIENCE Creating a Line Graph 130
Pressure depends on force and area. 131CHAPTER INVESTIGATION Pressure in Fluids 136
Fluids can exert a force on objects. 138
Work and Energy 148
Work is the use of force to move an object. 151MATH IN SCIENCE Working with Averages 156
Energy is transferred when work is done. 157THINK SCIENCE How Do They Do It? 165
Power is the rate at which work is done. 166CHAPTER INVESTIGATION Work and Power 172
Temperature and Heat 182
Temperature depends on particle movement. 185MATH IN SCIENCE Metric Conversions 191
Energy flows from warmer to cooler objects. 192SCIENCE ON THE JOB Cooking with Heat 197
The transfer of energy as heat can be controlled. 198CHAPTER INVESTIGATION Insulators 204
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Energy is transferredwhen a force moves
an object.
Heat is a flow of energy dueto temperature differences.
Chemical Interactions
A substance’s atomic struc-ture determines its physical
and chemical properties.
FL10 McDougal Littell Science Grade 8
UNIT 2
Atomic Structure and the Periodic Table 220
Atoms are the smallest form of elements. 223CONNECTING SCIENCES Elements of Life 230
Elements make up the periodic table. 231CHAPTER INVESTIGATION Modeling Atomic Masses 238
The periodic table is a map of the elements. 240MATH IN SCIENCE Using Scientific Notation 247
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FRONTIERS IN SCIENCE Medicines from Nature 212
FLORIDA CONNECTION Plant Medicines from Florida 216
TIMELINES IN SCIENCE The Story of Atomic Structure 280
This is an extremelyclose-up view of nickel. How do thingslook different thecloser you get tothem? page 220
Table of Contents FL11
Chemical reactions formnew substances by breakingand making chemical bonds.
Chemical Bonds and Compounds 252
Elements combine to form compounds. 255MATH IN SCIENCE Calculating Ratios 260
Chemical bonds hold compounds together. 261THINK SCIENCE Stick to It 269
Substances’ properties depend on their bonds. 270CHAPTER INVESTIGATION Chemical Bonds 274
Chemical Reactions 284
Chemical reactions alter arrangements of atoms. 287MATH IN SCIENCE Analyzing Line Graphs 295
The masses of reactants and products are equal. 296SCIENCE ON THE JOB Chemistry in Firefighting 303
Chemical reactions involve energy changes. 304CHAPTER INVESTIGATION Exothermic or Endothermic? 310
Life and industry depend on chemical reactions. 3124
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Visual Highlights
The Periodic Table of the Elements 234Comparing Bonds 266Balancing Equations with Coefficients 301
The properties of compoundsdepend on their atoms and
chemical bonds.
How do these skydiversstay together? How isthis similar to the wayatoms stay together?page 252
Waves, Sound, and Light
Waves transfer energy andinteract in predictable ways.
Sound waves transfer energythrough vibrations.
How is this guitarplayer producingsound? page 360
Waves 332
Waves transfer energy. 335MATH IN SCIENCE Mean, Median, and Mode 341
Waves have measurable properties. 342CHAPTER INVESTIGATION Wavelength 348
Waves behave in predictable ways. 350CONNECTING SCIENCES Tsunamis! 355
Sound 360
Sound is a wave. 363EXTREME SCIENCE Sonic Booms 370
Frequency determines pitch. 371
Intensity determines loudness. 378MATH IN SCIENCE Interpreting Graphs 383
Sound has many uses. 384CHAPTER INVESTIGATION Build a Stringed Instrument 390
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FL12 McDougal Littell Science Grade 8
UNIT 3
Unit Features
FRONTIERS IN SCIENCE Sound Medicine 324
FLORIDA CONNECTION Listening to Dolphins 328
TIMELINES IN SCIENCE The Story of Light 432
Table of Contents FL13
Electromagnetic wavestransfer energy through
radiation.
How does thisphone stay connected? page 396
Optical tools depend on thewave behavior of light.
Electromagnetic Waves 396
Electromagnetic waves have unique traits. 399MATH IN SCIENCE Using Exponents 404
Electromagnetic waves have many uses. 405THINK SCIENCE Are Cell Phones Harmful? 413
The Sun is the source of most visible light. 414
Light waves interact with materials. 419CHAPTER INVESTIGATION Wavelength and Color 426
Light and Optics 436
Mirrors form images by reflecting light. 439MATH IN SCIENCE Measuring Angles 444
Lenses form images by refracting light. 445CHAPTER INVESTIGATION Looking at Lenses 450
The eye is a natural optical tool. 452
Optical technology makes use of light waves. 457SCIENCE ON THE JOB Optics in Photography 465
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Visual Highlights
Graphing a Wave 345Sound Frequencies Heard by Animals 373How Musical Instruments Work 387The Electromagnetic Spectrum 406How a Convex Lens Forms an Image 448Microscopes and Telescopes 459
Chapter 2: Sound 61
The way a musical instrument vibrates when it isplayed determines the sound it produces.
How Musical Instruments Work
Wind Instruments
Stringed Instruments
Percussion Instruments
Musicians play a drum bystriking a tightly stretchedskin. The vibrations of thetight skin send out soundwaves. The size and tightness of the drum skin determine the pitch.
Musicians play the trombone by blowing into amouthpiece. Sound waves are produced by acolumn of vibrating air. Like the length of amusical string, the length of the air columndetermines the pitch.
Stringed instruments, such as the guitar, are played by plucking the strings. The plucking starts the vibrations that produce sound waves.
The vibrations beginwhen a player plucksone of the strings.
The vibrations travel through thebridge to the soundboard, whichmakes the entire soundboard vibrate.
As the soundboard vibrates, theair inside the body also vibrates,which amplifies the sound waves.
The sound waves exitthe guitar throughthe sound hole.
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To play a differentpitch, the playerpresses on a stringto shorten it. Ashorter string pro-duces a higher pitch.
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bridge
soundboard
sound hole
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UNIT 4
Heredity and Human Development
Organisms grow, reproduce,and maintain themselves
through cell division.
In sexual reproduction,genes are passed from parents to offspring in
predictable patterns.
Cell Division 480
Cell division occurs in all organisms. 483CONNECTING SCIENCES Chemical Dyes Show Nerve Growth 489
Cell division is part of the cell cycle. 490CHAPTER INVESTIGATION Stages of the Cell Cycle 496
Both sexual and asexual reproduction involve cell division. 498
MATH IN SCIENCE Using Exponents 503
Patterns of Heredity 508
Living things inherit traits in patterns. 511CHAPTER INVESTIGATION Offspring Models 515
Patterns of heredity can be predicted. 520MATH IN SCIENCE Using Punnett Squares 526
Meiosis is a special form of cell division. 527THINK SCIENCE Are Traits Linked? 533
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Unit Features
FRONTIERS IN SCIENCE Genes That Map the Body 472
FLORIDA CONNECTION Loggerhead Turtles 476
TIMELINES IN SCIENCE The Story of Genetics 538
What similarities canyou see between thismother wolf and hertwo offspring? page 508
FL14 McDougal Littell Science Grade 8
Table of Contents FL15
DNA and Modern Genetics 542
DNA and RNA are required to make proteins. 545CHAPTER INVESTIGATION Extract and Observe DNA 552
Changes in DNA can produce variation. 554MATH IN SCIENCE Finding Percent of a Whole 559
Modern genetics uses DNA technology. 560EXTREME SCIENCE Modern Genetics Meets the Dodo and the Solitaire 565
Control and Reproduction 570
The nervous system responds and controls. 573CHAPTER INVESTIGATION Are You a Supertaster? 580
The endocrine system helps regulate body conditions. 582CONNECTING SCIENCES Heating and Cooling 589
The reproductive system allows the production of offspring. 590
MATH IN SCIENCE Solving Proportions 597
Growth, Development, and Health 602
The human body changes over time. 605SCIENCE ON THE JOB Aging the Face 611
Systems in the body function to maintain health. 612MATH IN SCIENCE Choosing a Data Display 619
Science helps people prevent and treat disease. 620CHAPTER INVESTIGATION Cleaning Your Hands 626
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DNA is a set of instructionsfor making cell parts.
The nervous and endocrinesystems allow the body to
respond to internal andexternal conditions.
The body develops andmaintains itself over time.
Visual Highlights
Cell Division 493Punnett Square and Probability 523Meiosis 531Translation 550Growth of the Fetus 595Pathogens and Disease 623
What caused these rails to bend, and how long did it take? page 750
The Changing Earth
Minerals are basic buildingblocks of Earth.
FL16 McDougal Littell Science Grade 8
UNIT 5
Rocks change into otherrocks over time.
Minerals 642
Minerals are all around us. 645MATH IN SCIENCE Writing Fractions as Percents 651
A mineral is identified by its properties. 652CHAPTER INVESTIGATION Mineral Identification 660
Minerals are valuable resources. 662SCIENCE ON THE JOB Geometry for Gems 669
Rocks 674
The rock cycle shows how rocks change. 677EXTREME SCIENCE Rocks from Space 683
Igneous rocks form from molten rock. 684MATH IN SCIENCE Estimating Area 690
Sedimentary rocks form from earlier rocks. 691
Metamorphic rocks form as existing rocks change. 698CHAPTER INVESTIGATION Rock Classification 704
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Unit Features
FRONTIERS IN SCIENCE Studying Volcanoes 634with Satellites
FLORIDA CONNECTION Florida’s Keys and Barrier Islands 638
TIMELINES IN SCIENCE The Story of Fossils 710
Table of Contents FL17
The movement of tectonicplates causes geologic
changes on Earth.
Earthquakes release stressthat has built up in rocks.
Mountains and volcanoes form as
tectonic plates move.
Plate Tectonics 714
Earth has several layers. 717
Continents change position over time. 722CHAPTER INVESTIGATION Convection Currents and
Plate Movement 728
Plates move apart. 730MATH IN SCIENCE Calculating Equivalent Rates 737
Plates converge or scrape past each other. 738THINK SCIENCE What on Earth Is Happening Here? 745
Earthquakes 750
Earthquakes occur along faults. 753EXTREME SCIENCE When Earth Shakes 758
Earthquakes release energy. 759MATH IN SCIENCE Multiplication 767
Earthquake damage can be reduced. 768CHAPTER INVESTIGATION How Structures React
in Earthquakes 776
Mountains and Volcanoes 782
Movement of rock builds mountains. 785MATH IN SCIENCE Calculating the Mean of a Data Set 793
Volcanoes form as molten rock erupts. 794CHAPTER INVESTIGATION Make Your Own Volcanoes 802
Volcanoes affect Earth’s land, air, and water. 804SCIENCE ON THE JOB Rangers at Yellowstone 811
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Visual Highlights
Mineral Formation 665The Rock Cycle 681Tectonic Plate Boundaries 743Seismic Waves 763Formation of the Himalayas 789
How does new land form frommolten rock? page 782
Features
FL18 McDougal Littell Science Grade 8
Math in Science
NATURE OF SCIENCEMaking Stem-and-Leaf Plots 22
MOTION AND FORCESWorking with Units 64Using Significant Figures 96Creating a Line Graph 130Working with Averages 156Metric Conversions 191
CHEMICAL INTERACTIONSUsing Scientific Notation 247Calculating Ratios 260Analyzing Line Graphs 295
WAVES, SOUND, AND LIGHTMean, Median, and Mode 341Interpreting Graphs 383Using Exponents 404Measuring Angles 444
HEREDITY AND HUMAN DEVELOPMENTUsing Exponents 503Using Punnett Squares 526Finding Percent of a Whole 559Solving Proportions 597Choosing a Data Display 619
THE CHANGING EARTHWriting Fractions as Percents 651Estimating Area 690Calculating Equivalent Rates 737Multiplication 767Calculating the Mean of a Data Set 793
Think Science
MOTION AND FORCESEvaluating Hypotheses 88Isolating Variables 165
CHEMICAL INTERACTIONSIsolating Variables 269
WAVES, SOUND, AND LIGHTDetermining Relevance 413
HEREDITY AND HUMAN DEVELOPMENTDetermining Relevance 533
THE CHANGING EARTHEvaluating Conclusions 745
Connecting Sciences
CHEMICAL INTERACTIONSPhysical Science and Life Science 230
WAVES, SOUND, AND LIGHTPhysical Science and Earth Science 355
HEREDITY AND HUMAN DEVELOPMENTLife Science and Physical Science 489Life Science and Physical Science 589
Wave HeightsTracking stations throughout the world’s oceans measure andrecord the height of water waves that pass beneath them. The data recorded by the stations can be summarized as average waveheights over one hour or one day.
How would you summarize the typical wave heights over one week?There are a few different ways in which data can be summarized.Three common ways are finding the mean, median, and mode.
Use the data to answer the following questions.
The data below show wave heights taken from a station off the coast of Florida over two weeks.
1. Find the mean, median, and mode of the data for Week 1.
2. Find the mean, median, and mode of the data for Week 2.
CHALLENGE A storm carrying strong winds caused highwaves on the fifth day of the data shown above for Week 1.Which of the following was most affected by the highvalue—the mean, median, or mode?
SKILL: MEAN, MEDIAN, AND MODE
Wk 1 1.2 m 1.1 m 1.1 m 1.5 m 4.7 m 1.2 m 1.1 m
Wk 2 0.7 m 0.8 m 0.9 m 0.8 m 1.0 m 1.1 m 0.8 m
ExampleWave height data for one week are shown below.
(1) Mean To find the mean of the data, divide the sum of the values by the number of values.
Mean = = 1.5 m
ANSWER The mean wave height is 1.5 m.
(2) Median To find the median of the data, write the values in orderfrom least to greatest. The value in the middle is the median.
1.2 m 1.3 m 1.4 m 1.4 m 1.5 m 1.7 m 2.0 m
ANSWER The median wave height is 1.4 m.
(3) Mode The mode is the number that occurs most often.
ANSWER The mode for the data is also 1.4 m.
1.2 + 1.5 + 1.4 + 1.7 + 2.0 + 1.4 + 1.3�����
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1.2 m 1.5 m 1.4 m 1.7 m 2.0 m 1.4 m 1.3 m
MATH TUTORIALCLASSZONE.COM
Click on Math Tutorial formore help with finding themean, median, and mode.
Chapter 1: Waves 15
Before going out on the water, boaters can check reports on wave conditions in their area.
Table of Contents FL19
Science on the Job
MOTION AND FORCESPhysics for Rescuers 55Cooking with Heat 197
CHEMICAL INTERACTIONSChemistry in Firefighting 303
WAVES, SOUND, AND LIGHTOptics in Photography 465
HEREDITY AND HUMAN DEVELOPMENTAging the Face 611
THE CHANGING EARTHGeometry for Gems 669Rangers at Yellowstone 811
Extreme Science
NATURE OF SCIENCECarbon Nanotubes 31
MOTION AND FORCESBending Light 124
WAVES, SOUND, AND LIGHTSonic Booms 370
HEREDITY AND HUMAN DEVELOPMENTModern Genetics Meets the Dodo and the Solitare 565
THE CHANGING EARTHRocks from Space 683When Earth Shakes 758
Frontiers in Science
MOTION AND FORCESRobots on Mars 38
CHEMICAL INTERACTIONSMedicines from Nature 212
WAVES, SOUND, AND LIGHTSound Medicine 324
HEREDITY AND HUMAN DEVELOPMENTGenes That Map the Body 472
THE CHANGING EARTHStudying Volcanoes with Satellites 634
Florida Connections
MOTION AND FORCESCatching a Draft: The Physics of Stock Car Racing 42
CHEMICAL INTERACTIONSPlant Medicines from Florida 216
WAVES, SOUND, AND LIGHTListening to Dolphins 328
HEREDITY AND HUMAN DEVELOPMENTLoggerhead Turtles 476
THE CHANGING EARTHFlorida’s Keys and Barrier Islands 638
Timelines in Science
MOTION AND FORCESAbout Temperature and Heat 178
CHEMICAL INTERACTIONSThe Story of Atomic Structure 280
WAVES, SOUND, AND LIGHTThe Story of Light 432
HEREDITY AND HUMAN DEVELOPMENTThe Story of Genetics 538
THE CHANGING EARTHThe Story of Fossils 710
Chapter 3: Chemical Reactions 85
Some fires involve metals such asmagnesium. This metal burns at avery high temperature and reacts violently with water. Firefighters tryto smother metal fires with a material such as sand.
Metal Fires
Some fires can be extinguished by a chemical reaction. In kitchen grease fires, the chemicals that are used to fight the fire react with the grease. The reaction produces a foam that puts out the fire.
The fire shown above is a magnesiumfire in Chicago in 1998. Firefightersused water to protect surroundingbuildings, but dumped road salt onthe burning magnesium.
Chemistry in Firefighting A firefighter’s job may seem simple: to put out fires. However, a firefighter needs to know about chemicals and chemical reactions. A fire is a combustion reaction that requires oxygen as a reactant.Without oxygen, a fire will normally burn itself out, so firefighterstry to prevent oxygen from reaching the burning substances.Firefighters often use water or carbon dioxide for this purpose, butthese materials make some types of fires more dangerous.
FIREFIGHTER
EXPLORE
Build a carbon dioxide fire extinguisher.
1. Put 3 tsp of baking soda on a tissue and roll it into a tube. Tie the ends and middle of the tube with thread. Leave extra thread at one end of the tube.
2. Mold clay tightly around the straw.
3. Pour some vinegar into a bottle.
4. Hold the thread to suspend the tissue tube above thevinegar. Place the straw inside the bottle. Use the claymolded around the straw to hold the thread in place. Be sure that the straw is not touching the vinegar.
5. Shake and observe the fire extinguisher.
Grease Fires
Hazardous Reactions
Chemicals may react with water to form poisonous gases or acids.
Firefighters might use a foam thatextinguishes the fire, cools the
area around the fire, and traps gasesreleased by the fire. The symbolsshown on the left are among severalthat show firefighters what chemicaldangers may be present.
FL20 McDougal Littell Science Grade 8
Simulations
MOTION AND FORCESChanging Acceleration 71Applying Force 79Newton’s Second Law 90Fluids and Pressure 133Work 149Kinetic Energy and Temperature 183Conduction, Convection, or Radiation 201
CHEMICAL INTERACTIONSBuild an Atom 226
WAVES, SOUND, AND LIGHTForces and Waves 333The Sun at Different Wavelengths 397Using Lenses to Form Images 449
HEREDITY AND HUMAN DEVELOPMENTStages of Cell Division 481Mendel’s Experiment 509Punnett Squares 521
THE CHANGING EARTHRock Cycle 675Create a Volcanic Eruption 783
Visualizations
MOTION AND FORCESRelative Motion 47Effect of Gravity in a Vacuum 119Transfer of Potential and Kinetic Energy 162
CHEMICAL INTERACTIONSRadioactive Decay 246Ionic and Covalent Bonds 253Polar Electron Cloud 265Concentration and Reaction Rate 292Endothermic and Exothermic Reactions 308
WAVES, SOUND, AND LIGHTWave Graphing 344How Sound Travels 361Doppler Effect 377Electromagnetic Waves 400Reflection 441
HEREDITY AND HUMAN DEVELOPMENTMitosis 492Protein Synthesis 551Fertilization and Implantation 592
of an Egg CellHuman Aging 603
THE CHANGING EARTHCrystal Growth 648Igneous Crystal Formation 686Continental Movement over Time 724Plate Boundaries 741Fault Motion 757Primary-Wave and Secondary-Wave Motion 767Erupted Volcanic Material 796
Career Centers
Mechanical Engineering 41
Chemistry 215
Audiology 327
Molecular Biology 475
Volcanology 637
Internet Resources @ ClassZone.com
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Table of Contents FL21
Resource Centers
NATURE OF SCIENCEResources for the following topics may be found atClassZone.com: New Uses of Existing Technology;Expanding on an Old Theory; Risks and Benefits ofNew Technology; Nanotubes.
MOTION AND FORCESResources for the following topics may be found atClassZone.com: Stock Car Racing; Finding Position;Acceleration; Inertia; Moving Rocks; Newton’s Lawsof Motion; Momentum; Gravity; GravitationalLenses; Friction, Forces, and Surfaces; Work; Power;Temperature and Heat Research; Temperature andTemperature Scales; Thermal Energy.
CHEMICAL INTERACTIONSResources for the following topics may be found atClassZone.com: Florida’s Medicinal Plants; PeriodicTable; Atom; Elements Important to Life; ChemicalFormulas; Properties of Ionic and CovalentCompounds; Atomic Research; Balancing ChemicalEquations; Catalysts in Living Things.
WAVES, SOUND, AND LIGHTResources for the following topics may be found atClassZone.com: Dolphin Therapy; Waves; WaveSpeed; Supersonic Aircraft; Sound Safety; MusicalInstruments; The Electromagnetic Spectrum; VisibleLight; Light Research; Optics; Microscopes andTelescopes; Lasers.
HEREDITY AND HUMAN DEVELOPMENTResources for the following topics may be found atClassZone.com: Loggerhead Turtles; NerveRegeneration; Cell Cycle; Asexual Reproduction;Sexual Reproduction; Meiosis; Genetics Research;Human Genome Project; DNA; Mutations; DNATechnology; Senses; Nervous System; EndocrineSystem; Human Health; Nutrition; Fighting Disease.
THE CHANGING EARTHResources for the following topics may be found atClassZone.com: Florida Keys and Barrier Islands;Precious Metals; Minerals; Gemstones; Meteoritesand Impacts; Igneous Rocks; Sedimentary Rocks;Metamorphic Rocks; Fossil Research and Excavation;Earth’s Interior; Effects of Plate Movement; RecentEarthquakes; Seismology; Tsunamis; EarthquakeEngineering; Historic and Current Volcanic Eruptions;Effects of Volcanic Eruptions.
Math Tutorials
NATURE OF SCIENCEStem-and-Leaf Plots 22
MOTION AND FORCESUnits and Rates 64Rounding Decimals 96Creating a Line Graph 130Finding the Mean 156Temperature Conversions 191
CHEMICAL INTERACTIONSScientific Notation 247Ratios 260Interpreting Line Graphs 295
WAVES, SOUND, AND LIGHTFinding the Mean, Median, and Mode 341Interpreting Line Graphs 383Positive and Negative Exponents 404Measuring Angles 444
HEREDITY AND HUMAN DEVELOPMENTExponents 503Probability 526The Percent Equation 559Solving Proportions 597Choosing a Data Display 619
THE CHANGING EARTHPercents and Fractions 651Estimating Area 690Rates 737Multiplication 767Finding the Mean 793
NSTA SciLinks
Codes for use with the NSTA SciLinks site maybe found on every chapter opener.
Florida Review
There is a content review and FCAT practice forevery chapter at ClassZone.com.
Nature of Science
Up and Down; Flying High 3
Motion and Forces
Off the Wall; Rolling Along 47Popping Ping-Pong Balls; Take Off! 79Let It Slide; Under Pressure 115Bouncing Ball; Power Climbing 149Moving Colors; Does It Chill? 183
Chemical Interactions
That’s Far! Element Safari 221Mixing It Up; The Shape of Things 253Changing Steel Wool; A Different Rate 285
Waves, Sound, and Light
How Can Energy Be Passed Along? How Can You Change a Wave? 333
What Gives a Sound Its Qualities? How Does Size Affect Sound? 361
What Melts the Ice Cubes? What Is White Light Made Of? 397
How Does a Spoon Reflect Your Face? Why Do Things Look Different Through Water? 437
Heredity and Human Development
Dividing to Multiply; Division Math 481How Are Traits Distributed? Combinations 509What Is the Pattern? What Vegetable
Is That? 543Color Confusion; Eggs 571How Much Do You Exercise? How Safe
Is Your Food? 603
The Changing Earth
How Do You Turn Water into a Mineral? What Makes Up Rocks? 643
How Can Rocks Disappear? What Causes Rocks to Change? 675
Watching a Pot Boil; Earth’s Moving Surface 715Can You Bend Energy? How Can
Something Move Forward, Yet Sideways? 751Making Mountains; Under Pressure 783
Explore the Big IdeaExplore the Big IdeaChapter Opening Inquiry
Each chapter opens with hands-on explorations that introduce the chapter’s Big Idea.
Chapter 1: The Nature of Science 3
Up and DownFill a clear plastic cup about 2/3 fullof water. Slowly pour a thick layer ofvegetable oil on top of thewater. Sprinkle a tea-spoon of salt intothe cup, and carefullyobserve what happens.
Observe and Think What do youthink is happening to the oil? How couldyou test your idea?
Flying HighMake two differenttypes of paper airplanes. Take one in each hand and throwthem together. Now holdeach plane in the other handand throw them again. Werethe results always the same?Repeat the experiment until you are fairly certain which plane usually flies farthest.
Observe and Think How many times did you have to repeat the experiment? Why was it important to switch the planes from hand to hand?
Internet Activity: TechnologyGo to ClassZone.com to discover how technologydeveloped for one application can be adaptedand applied to other situations.
Observe and ThinkHow was the technologyoriginally used? In whatways is the technologyused now? Can you thinkof other ways to use it?
NSTA scilinks.org
Technology Code: MDL070
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Prepare and practice for the FCAT
• Section Reviews, pp. 11, 21, 30
• Chapter Review, pp. 32–34• FCAT Practice, p. 35
CLASSZONE.COM• Florida Review: Content
Review and FCAT Practice
2 Chapter 1: The Nature of Science
The Natureof Science
Scientists use many different processesand tools to study thenatural world.
Key Concepts
Science is an ongoingprocess.Learn how scientific ideasdevelop and change.
Scientists use tools to analyze and communicate.Learn about some of the tech-niques and tools scientists use.
Science and technologyare interrelated.Find out how technologicaladvances help science andhow science helps technologi-cal advances.
3SECTION
2SECTION
1SECTION
What patterns do you notice in this picture?
FL22 McDougal Littell Science Grade 8
Nature of Science
Mixing Substances 12
Motion and Forces
Acceleration and Slope 72Newton’s Laws of Motion 102Pressure in Fluids 136Work and Power 172Insulators Design Your Own 204
Chemical Interactions
Modeling Atomic Masses 238Chemical Bonds 274Exothermic or Endothermic? 310
Waves, Sound, and Light
Wavelength 348Build a Stringed
Instrument Design Your Own 390Wavelength and Color 426Looking at Lenses 450
Heredity and Human Development
Stages of the Cell Cycle 496Offspring Models 518Extract and Observe DNA 552Are You a Supertaster? 580Cleaning Your Hands 626
The Changing Earth
Mineral Identification 658Rock Classification 704Convection Currents and Plate Movement 728How Structures React
in Earthquakes Design Your Own 776Make Your Own Volcanoes 802
Chapter InvestigationsChapter InvestigationsFull-Period Labs
The Chapter Investigations are in-depth labs thatlet you form and test a hypothesis, build a model,or sometimes design your own investigation.
Table of Contents FL23
Nature of Science
Assumptions 5Small Samples 14
Motion and Forces
Location 49Speed 56Changing Motion 81Acceleration 89Collisions 104Downward Acceleration 117Pressure 131Forces in Liquid 138Work 151Power 166Temperature 185Conduction 198
Chemical Interactions
The Size of Atoms 223Similarities and Differences of Objects 231Compounds 255Bonds in Metals 270Chemical Changes 287Energy Changes 304
Waves, Sound, and Light
Waves 335Reflection 350Sound 363Pitch 371Echoes 384Electromagnetic Waves 399
Radio Waves 405Light and Matter 419Reflection 439Refraction 445Focusing Vision 452Combining Lenses 457
Heredity and Human Development
Cell Division 483Probability 520Meiosis 527Templates 545Codes 554Smell 573Reproduction 590Growth 605The Immune System 620
The Changing Earth
Minerals 645Minerals at Your Fingertips 662Rocks and Minerals 677Particle Layers 691Density 717Movements of Continents 722Divergent Boundaries 730Tectonic Plates 738Pressure 753Movement of Energy 759Shaking 768Folding 785Eruptions 794
ExploreExploreIntroductory Inquiry Activities
Most sections begin with a simple activity that lets youexplore the Key Concept before you read the section.
Chapter 1: The Nature of Science 5
Science is a process.You can think of science as a continuous process of asking questionsabout the world and seeking answers to those questions. Scientists usemany processes. Typically, scientists studying a topic ask questions,determine what is known about the topic, investigate, interpret theirresults, and share their results. As more knowledge becomes available,scientists also see how this new knowledge affects their ideas. Scientistsare always building on old knowledge and interpreting results in different ways on the basis of new knowledge.
Check Your Reading List five steps that scientists usually take as part of the scientific process.
VOCABULARY
hypothesis p. 6law p. 6
BEFORE, you learned
• Science is a way to explore thenatural world
• Science is based on objectiveobservation
• Scientific ideas can be tested
NOW, you will learn
• What processes scientists use• How scientists use patterns• How scientific ideas change
with time
EXPLORE Assumptions
Can you recognize your assumptions?
PROCEDURE
Use the six toothpicks to make an equilateral triangle, one in which all three sides are the same length.
Now use the same six toothpicks to make two equilateral triangles.
Use the same six toothpicks to make four equilateral triangles.
WHAT DO YOU THINK?• What did you assume, or take for granted, about the
triangles you were forming?• Were you able to do step 3? If not, try to think of more
assumptions you may have unknowingly made. Is there any reason to believe these assumptions are true?
3
2
1
KEY CONCEPT
Science is an ongoingprocess.
Sunshine StateSTANDARDSSC.H.1.3.1: The studentknows that scientificknowledge is subject tomodification as newinformation challengesprevailing theories andas a new theory leads tolooking at old observa-tions in a new way.SC.H.1.3.2: The studentknows that the studyof the events that ledscientists to discoveriescan provide informa-tion about the inquiryprocess and its effects.SC.H.2.3.1: The studentrecognizes that pat-terns exist within andacross systems.
MATERIALS6 toothpicks
FL24 McDougal Littell Science Grade 8
InvestigateInvestigateSkill Labs
Each Investigate activity gives you a chance to practice a specificscience skill related to the content that you’re studying.
Nature of Science
Patterns Inferring 7Multiple Trials Measuring 17Constraints and Criteria Design Your Own 25
Motion and Forces
Changing Positions Observing 52Speed and Distance Design Your Own 59Acceleration Measuring 67Inertia Design Your Own 86Motion and Force Hypothesizing 94Newton’s Third Law Observing 98Momentum Observing 106Gravity Predicting 122Friction in Air Design Your Own 128Bernoulli’s Principle Observing 140Work Measuring 154Mechanical Energy Analyzing data 161Power Measuring 169Temperature Measurements Modeling 189Heat Transfer Measuring 194
Chemical Interactions
Masses of Atomic Particles Modeling 227
Radioactivity Modeling 245Element Ratios Modeling 257Crystals Observing 267Chemical Reactions Inferring 292Conservation of Mass Measuring 297Sugar Combustion Inferring 313
Waves, Sound, and Light
Wave Types Comparing 339Frequency Collecting data 346Diffraction Predicting 352Sound Energy Observing 367Sound Frequency Inferring 374
Loudness Observing 379Wave Behavior Design Your Own 402The Electromagnetic
Spectrum Drawing conclusions 410Artificial Lighting Design Your Own 416Mixing Colors Observing 424The Law of Reflection Analyzing 441Vision Observing 454Optical Tools Design Your Own 460
Heredity and Human Development
Chromosomes Making models 486Cell Division Making models 494Asexual Reproduction Drawing conclusions 501Multiple Probabilities Analyzing data 524Fertilization Design Your Own 529Neutral Mutations Making models 556Response to Exercise Observing 586Life Expectancy Graphing 609Food Labels Analyzing 615
The Changing Earth
Crystal Shape Observing 648Hardness of Minerals Classifying 658Mining Drawing conclusions 667Classification of Rocks Classifying 679Crystal Size Analyzing 687Rock Layers Modeling 696Metamorphic Changes Modeling 700Earth’s Different Layers Modeling 720Magnetic Reversals Modeling 733Convergent Boundaries Design Your Own 741
Faults Modeling 755Subduction-Zone Earthquakes Analyzing 761Fault-Block Mountains Modeling 790Mudflows Analyzing 807
Table of Contents FL25