grade 7 florida science - classzone
TRANSCRIPT
FL7
The Nature of Science 2
Basic tools of science are universal. 5CONNECTING SCIENCES The Science of Clean Water 13
Scientific ideas are based on evidence. 14CHAPTER INVESTIGATION Using a Filter 22
Scientists belong to a world community. 24MATH IN SCIENCE Making Bar Graphs 31
Saving Coral 42
Florida’s Sinkholes 190
Animatronics 334
The Ultimate Fish 450
A Place in the Sun 564
Cape Canaveral: Step to the Stars 666
Student Resources
Florida Resources 809Florida Content Review/Preview 811FCAT Science Reference 823Appendix 825
Student Resource Handbooks R1Scientific Thinking Handbook R2Lab Handbook R10Math Handbook R36Note-Taking Handbook R45
Glossary R52Index R74Acknowledgments R117
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Introducing Science FL26
Unifying Principles of Science FL30Florida Student Handbook FL36
GRADE 7
Florida Science
604 Unit 1: Earth’s Waters
Sunshine State Standards
In “Saving Coral” you’ll read how organismscalled polyps grow, die, and decay, leaving skeletons that form coral reefs. (SC.D.1.3.2)
Slight changes in a reef ecosystem can havelong-term effects on population size.(SC.G.2.3.3)
FLORIDA CONNECTIONS
The Water Planet 46
Water continually cycles. 49THINK SCIENCE Does Mars Have a Water Cycle? 55
Fresh water flows and freezes on Earth. 56MATH IN SCIENCE Multiplying Fractions and Whole Numbers 63
Fresh water flows underground. 64CHAPTER INVESTIGATION Water Moving Underground 72
Freshwater Resources 78
Fresh water is an essential resource. 81MATH IN SCIENCE Volume of Rectangular Prisms 89
Society depends on clean and safe water. 90CHAPTER INVESTIGATION Monitoring Water Quality 98
Water shortages threaten society. 100SCIENCE ON THE JOB Water and Farming 107
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Earth’s Waters
Water moves throughEarth’s atmosphere, oceans,
and land in a cycle.
Fresh water is a limitedresource and is essential
for human society.
UNIT 1
In what ways do youdepend on water?page 78
FL8 McDougal Littell Science
Unit Features
FRONTIERS IN SCIENCE Exploring the Water Planet 38
FLORIDA CONNECTION Saving Coral 42
TIMELINES IN SCIENCE Exploring the Ocean 146
Table of Contents FL9
Visual Highlights
The oceans are a connectedsystem of water in motion.
Springs and Wells 69Sources of Water Pollution 95The Ocean Floor 120Ocean Waves 131Intertidal Zone 155Coral Reefs 163Life in the Open Ocean 167
Ocean Systems 112
The oceans are a connected system. 115MATH IN SCIENCE Plotting Coordinates 123
Ocean water moves in currents. 124
Waves move through oceans. 129CHAPTER INVESTIGATION Wave Movement 134
Waters rise and fall in tides. 136CONNECTING SCIENCES Tidal Energy 141
Ocean Environments 150
Ocean coasts support plant and animal life. 153MATH IN SCIENCE Making a Double Bar Graph 160
Conditions differ away from shore. 161EXTREME SCIENCE Undersea Hot Spots 169
The ocean contains natural resources. 170CHAPTER INVESTIGATION Population Sampling 178
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The ocean supports life andcontains natural resources.
What causes thesewaves? page 112
Waves transport energy, not water. As a wave crest passes, thewater particles move in circular paths.
Ocean Waves
Chapter 3: Ocean Systems 91
Wave Structure
The movement of the floatinginner tube is similar to themovement of the water particles.
Water particles rise as a wave crest approaches.
At the crest, water particles havemoved in a semicircle.
Water particles drop after thetrough passes.
The wave passes through thewater but the water particles endup in the same place they began.
wave direction
Below a certain depth,waves no longer affectthe water.
What happens to water particles as a wave passes through?
The deeper waterparticles move insmaller circles thanthe water particlesnear the surface.
water particlemovement
Wavelength is the distancebetween one wavecrest and the next.
Wave height is the vertical distance between the top of thecrest and the bottom of the trough.
C
Waves affect only thewater near the surface.
The troughis the lowpoint of thewave.
The crest isthe high pointof the wave.
Views of Earth Today 194
Technology is used to explore the Earth system. 197
Maps and globes are models of Earth. 203MATH IN SCIENCE Using Proportions 211
Topographic maps show the shape of the land. 212CHAPTER INVESTIGATION Investigate Topographic Maps 216
Technology is used to map Earth. 218THINK SCIENCE Which Site Is Best for an Olympic Stadium? 223
Weathering and Soil Formation 228
Mechanical and chemical forces break down rocks. 231MATH IN SCIENCE Surface Area of a Prism 237
Weathering and organic processes form soil. 238CHAPTER INVESTIGATION Testing Soil 246
Human activities affect soil. 248SCIENCE ON THE JOB Soil, Water, and Architecture 253
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Earth’s Surface
Modern technology haschanged the way we view
and map Earth.
Natural forces break rocksapart and form soil, which
supports life.
UNIT 2
Unit Features
FRONTIERS IN SCIENCE Remote Sensing 186
FLORIDA CONNECTION Florida’s Sinkholes 190
TIMELINES IN SCIENCE History of the Earth System 292
How is rock related tosoil? page 228
FL10 McDougal Littell Science Grade 7
Table of Contents FL11
Water, wind, and ice shapeEarth’s surface.
Society depends on naturalresources for energy and
materials.
Erosion and Deposition 258
Forces wear down and build up Earth’s surface. 261
Moving water shapes land. 266CHAPTER INVESTIGATION Creating Stream Features 272
Waves and wind shape land. 274CONNECTING SCIENCES Life on Dunes 280
Glaciers carve land and move sediments. 281MATH IN SCIENCE Creating a Line Graph 287
Natural Resources 296
Natural resources support human activity. 299CONNECTING SCIENCES Got Oil Spills? 307
Resources can be conserved and recycled. 308MATH IN SCIENCE Comparing Decimals 312
Energy comes from other natural resources. 313CHAPTER INVESTIGATION Wind Power 322
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Visual Highlights
Mechanical Weathering 233World Soil Types 241Organisms and Soil Formation 243Types of Glaciers and Movement 283Natural Resources 301
How do people obtainenergy from Earth’sresources? page 296
Electricity and Magnetism
Moving electric chargestransfer energy.
Circuits control the flow of electric charge.
How can circuits control theflow of charge? page 372
Electricity 338
Materials can become electrically charged. 341CONNECTING SCIENCES Electric Eels 349
Charges can move from one place to another. 350CHAPTER INVESTIGATION Lightning 358
Electric current is a flow of charge. 360MATH IN SCIENCE Using Variables 367
Circuits and Electronics 372
Charge needs a continuous path to flow. 375SCIENCE ON THE JOB The Science of Electrical Work 382
Circuits make electric current useful. 383MATH IN SCIENCE Solving Percent Problems 388
Electronic technology is based on circuits. 389CHAPTER INVESTIGATION Design an Electronic Communication Device 398
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FL12 McDougal Littell Science Grade 7
UNIT 3
Unit Features
FRONTIERS IN SCIENCE Electronics in Music 330
FLORIDA CONNECTION Animatronics 334
TIMELINES IN SCIENCE The Story of Electronics 404
Table of Contents FL13
Current can produce magnetism, and magnetism
can produce current.
What force is acting onthis compass needle?page 408
Magnetism 408
Magnetism is a force that acts at a distance. 411THINK SCIENCE Can Magnets Heal People? 419
Current can produce magnetism. 420
Magnetism can produce current. 427CHAPTER INVESTIGATION Build a Speaker 432
Generators supply electrical energy. 434MATH IN SCIENCE Using Significant Figures 439
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Visual Highlights
How a Photocopier Works 347How Lightning Forms 353Batteries 365How a PC Works 394How Magnets Differ from Other Materials 415How a Motor Works 425
Views of Earth’s Past 454
Earth’s past is revealed in rocks and fossils. 457CONNECTING SCIENCES Could T. Rex Win a Race? 464
Rocks provide a timeline for Earth. 465MATH IN SCIENCE Interpreting Graphs 472
The geologic time scale shows Earth’s past. 473CHAPTER INVESTIGATION Geologic Time 480
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Life Over Time
Rocks, fossils, and othertypes of natural evidence tell
Earth’s story.
FL14 McDougal Littell Science Grade 7
UNIT 4UNIT
Unit Features
FRONTIERS IN SCIENCE Life by Degrees 446
FLORIDA CONNECTION The Ultimate Fish 450
TIMELINES IN SCIENCE Life Unearthed 520
What does this footprinttell you about the animalthat left it? page 454
Table of Contents FL15
The History of Life on Earth 486
Earth has been home to living things for about 3.8 billion years. 489
MATH IN SCIENCE Using Proportions 496
Species change over time. 497CHAPTER INVESTIGATION Modeling Natural Selection 506
Many types of evidence support evolution. 508THINK SCIENCE How Did the Deep-Sea Angler Get Its Glow? 515
Population Dynamics 524
Populations have many characteristics. 527MATH IN SCIENCE Finding Averages 535
Populations respond to pressures. 536SCIENCE ON THE JOB Studying the Schools 543
Human populations have unique responses to change. 544CHAPTER INVESTIGATION Sustainable Resource
Management 552
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Living things, like Earth itself, change over time.
Populations are shaped by interactions
between organisms and the environment.
Visual Highlights
Fossils in Rocks 461Radioactive Breakdown 470Natural Selection 503Biological Evidence for Evolution 511
How do scientistslearn about the history of life onEarth? page 486
Systems, Support, and Movement 568
The human body is complex. 571THINK SCIENCE What Does the Body Need to Survive? 575
The skeletal system provides support and protection. 576MATH IN SCIENCE Comparing Rates 583
The muscular system makes movement possible. 584CHAPTER INVESTIGATION A Closer Look at Muscles 590
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The human body is made up of systems that work
together to perform necessary functions.
What materials doesyour body need tofunction properly?page 596
Human BiologyUNIT 5
FL16 McDougal Littell Science Grade 7
Unit Features
FRONTIERS IN SCIENCE Surprising Senses 560
FLORIDA CONNECTION A Place in the Sun 564
TIMELINES IN SCIENCE Seeing Inside the Body 624
Table of Contents FL17
Absorption, Digestion, and Exchange 596
The respiratory system gets oxygen and removes carbon dioxide. 599
SCIENCE ON THE JOB Breathing and Yoga 606
The digestive system breaks down food. 607MATH IN SCIENCE Choosing Units of Length 613
The urinary system removes waste materials. 614CHAPTER INVESTIGATION Modeling a Kidney 618
Transport and Protection 628
The circulatory system transports materials. 631CHAPTER INVESTIGATION Heart Rate and Exercise 638
The immune system defends the body. 640MATH IN SCIENCE Making a Line Graph 648
The integumentary system shields the body. 649EXTREME SCIENCE Artificial Skin 655
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Systems function to transport materials and
to defend and protect the body.
Red blood cells travel through ablood vessel. How do you thinkblood carries materials aroundyour body? page 628
Visual Highlights
The Skeletal System 579Muscle Tissue 587Respiratory System 603Digestive System 611Circulatory System 634
The skull protectsthe brain.
Twelve pairs ofribs protect thelungs and heart.
The vertebrae ofthe spinal columnprotect the spinalcord and supportthe cranium andother bones.
The kneecap iscalled the patella.
There are 26bones in the ankleand the foot.
The lower leg bonesare called the tibiaand the fibula.
The upper leg bone, calledthe femur, is the longestbone in the body.
The many bones in thewrist and the hand allow itto perform a great varietyof activities.
The lowerarm bonesare the ulnaand radius.
The upper arm bone iscalled the humerus.
The shoulderblade is calledthe scapula.
The lower jaw is theonly bone in the skullthat can move.
Chapter 1: Systems, Support, and Movement 17
Axial skeleton
Appendicularskeleton
The word appendicular has the same root as the word append, which means toattach. How do you think this word applies to the appendicular skeleton?
The skeletal system interacts with other body systems toallow this soccer player to stand, run, and kick.
The Skeletal System
Systems in the body obtainand process materials and
remove waste.
Space Science
People develop and usetechnology to explore
and study space.
Earth and the Moon move in predictable ways as
they orbit the Sun.
Exploring Space 670
Some space objects are visible to the human eye. 673
Telescopes allow us to study space from Earth. 679CHAPTER INVESTIGATION Observing Spectra 684
Spacecraft help us explore beyond Earth. 686MATH IN SCIENCE Using Exponents 694
Space exploration benefits society. 695CONNECTING SCIENCES How Earth’s Gravity Affects Plants 699
Earth, Moon, and Sun 704
Earth rotates on a tilted axis and orbits the Sun. 707CHAPTER INVESTIGATION Modeling Seasons 714
The Moon is Earth’s natural satellite. 716MATH IN SCIENCE Making Line Graphs 722
Positions of the Sun and Moon affect Earth. 723SCIENCE ON THE JOB Astronomy in Archaeology 731
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UNIT 6
What would you see if youlooked at the Moon with atelescope? page 704
FL18 McDougal Littell Science Grade 7
Unit Features
FRONTIERS IN SCIENCE Danger from the Sky 662
FLORIDA CONNECTION Cape Canaveral: Step to the Stars 666
TIMELINES IN SCIENCE The Story of Astronomy 736
Table of Contents FL19
Planets and other objects form a system
around our Sun.
Our Sun is one of billions ofstars in one of billions ofgalaxies in the universe.
Our Solar System 740
Planets orbit the Sun at different distances. 743MATH IN SCIENCE Using Percentages 748
The inner solar system has rocky planets. 749THINK SCIENCE What Shapes the Surface of Mars? 757
The outer solar system has four giant planets. 758
Small objects are made of ice and rock. 764CHAPTER INVESTIGATION Exploring Impact Craters 770
Stars, Galaxies, and the Universe 776
The Sun is our local star. 779CHAPTER INVESTIGATION Temperature, Brightness,
and Color 784
Stars change over their life cycles. 786MATH IN SCIENCE Interpreting a Scatter Plot 793
Galaxies have different sizes and shapes. 794EXTREME SCIENCE When Galaxies Collide 798
The universe is expanding. 7994
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Visual Highlights
Structures in the Universe 675Seasons 711Lunar Phases 725Objects in the Solar System 744Features of Rocky Planets 751Layers of the Sun 781Life Cycles of Stars 791
This image shows Jupiterwith one of its largemoons. How big arethese objects comparedwith Earth? page 740
Math in Science
NATURE OF SCIENCEMaking Bar Graphs 31
EARTH’S WATERSMultiplying Fractions and Whole Numbers 63Volume of Rectangular Prisms 89Plotting Coordinates 123Making a Double Bar Graph 160
EARTH’S SURFACEUsing Proportions 211Surface Area of a Prism 237Creating a Line Graph 287Comparing Decimals 312
ELECTRICITY AND MAGNETISMUsing Variables 367Solving Percent Problems 388Using Significant Figures 439
LIFE OVER TIMEInterpreting Graphs 472Using Proportions 496Finding Averages 535
HUMAN BIOLOGYComparing Rates 583Choosing Units of Length 613Making a Line Graph 648
SPACE SCIENCEUsing Exponents 694Making Line Graphs 722Using Percentages 748Interpreting a Scatter Plot 793
Think Science
EARTH’S WATERSDetermining Relevance 55
EARTH’S SURFACEInterpreting Data 223
ELECTRICITY AND MAGNETISMEvaluating Conclusions 419
LIFE OVER TIMEEvaluating Hypotheses 515
HUMAN BIOLOGYInferring 575
SPACE SCIENCEForming Hypotheses 757
Connecting Sciences
NATURE OF SCIENCEPhysical Science and Earth Science 13
EARTH’S WATERSEarth Science and Physical Science 141
EARTH’S SURFACEEarth Science and Life Science 208Earth Science and Life Science 307
ELECTRICITY AND MAGNETISMPhysical Science and Life Science 349
LIFE OVER TIMEEarth Science and Life Science 464
SPACE SCIENCEEarth Science and Life Science 699
Chapter 3: Freshwater Resources 89
Fish in an AquariumA fish requires a certain minimum amount of water to survive. If you plan to keep fish in an aquarium, you can calculate the volume of the aquarium to be sure it will contain enough water.
Find the volume of each aquarium. Give youranswer in liters.
1. The aquarium is 100 centimeters long, 50 centimeters wide, and 80 centimeters high.
2. The aquarium is 50 centimeters long, 20 centimeters wide, and 40 centimeters high.
3. The aquarium is 50 centimeters long, 40 centimeters wide, and 50 centimeters high.
CHALLENGE You are designing an aquarium to house severalfish of different species. The aquarium must hold 300 liters of water and fit in a space that is 100 centimeters long and50 centimeters wide. How high should the aquarium be?
MATH TUTORIALCLASSZONE.COM
Click on Math Tutorial formore help finding the vol-ume of a rectangular prism.
SKILL: VOLUME OF RECTANGULARPRISMS
Example
An aquarium is 50 centimeterslong, 30 centimeters wide, and 40 centimeters high. How many liters of water will it hold?
SolutionUse the formula for the volume of a rectangular prism.
Volume = length � width � height Write a word equation.
V = lwh Replace the words with variables.
= 50 cm � 30 cm � 40 cm Substitute 50 for l, 30 for w, and 40 for h.
= 60,000 cm3 Multiply. Note that cm3 is a cubic centimeter.
= 60,000 mL Each cubic centimeter holds a milliliter.
= 60 L Because there are 1000 milliliters in one liter, divide 60,000 by 1000.
ANSWER The aquarium holds 60 liters of water.
50 cm
40 cm
30 cm
Features
FL20 McDougal Littell Science Grade 7
Table of Contents FL21
Science on the Job
EARTH’S WATERSWater and Farming 107
EARTH’S SURFACESoil, Water, and Architecture 253
ELECTRICITY AND MAGNETISMThe Science of Electrical Work 382
LIFE OVER TIMEStudying the Schools 543
HUMAN BIOLOGYBreathing and Yoga 606
SPACE SCIENCEAstronomy in Archaeology 731
Extreme Science
EARTH’S WATERSUndersea Hot Spots 169
HUMAN BIOLOGYArtificial Skin 655
SPACE SCIENCEWhen Galaxies Collide 798
Frontiers in Science
EARTH’S WATERSExploring the Water Planet 38
EARTH’S SURFACERemote Sensing 186
ELECTRICITY AND MAGNETISMElectronics in Music 330
LIFE OVER TIMELife by Degrees 446
HUMAN BIOLOGYSurprising Senses 560
SPACE SCIENCEDanger from the Sky 662
Florida Connections
EARTH’S WATERSSaving Coral 42
EARTH’S SURFACEFlorida’s Sinkholes 190
ELECTRICITY AND MAGNETISMAnimatronics 334
LIFE OVER TIMEThe Ultimate Fish 450
HUMAN BIOLOGYA Place in the Sun 564
SPACE SCIENCECape Canaveral: Step to the Stars 666
Timelines in Science
EARTH’S WATERSExploring the Ocean 146
EARTH’S SURFACEHistory of the Earth System 292
ELECTRICITY AND MAGNETISMThe Story of Electronics 404
LIFE OVER TIMELife Unearthed 520
HUMAN BIOLOGYSeeing Inside the Body 624
SPACE SCIENCEThe Story of Astronomy 736
LANDSCAPE ARCHITECT
Soil, Water, andArchitectureLandscape architects design the landscapes around buildings and in parks. For example, they decide where to build sidewalks andwhere to place benches. Since flowing water can wash away soil,they try to control how water moves. They select plants, modify the slope of the land, and install drainage systems that will controlthe water. The plan below was used to build the park shown in the photographs.
EXPLORE
1. ANALYZE Examine the soil, drainage, plants, andother elements of the landscape of a park or the areaaround a building. Describe any areas where soil maywash away.
2. CHALLENGE Design a landscape surrounding a newschool, stadium, or other building. Draw a sketch andadd notes to explain your choices of locations for trees,sidewalks, and other features.
Chapter 7: Weathering and Soil Formation 253
Large oak trees were already growingon the land. The trees were left inplace to provide shade and help protect the soil.
Existing Plants
A landscape architect used a computer program to draw this plan for a park.The program is designed to make the plan look as if it were drawn by hand.
Plan for New Park
The landscape architect added mounds ofsoil planted with bushes to help divide theinside of the park from the roads around it.Stone walls hold the soil of the mounds in place. Without the walls, the soil wouldwash down onto the walkways.
Retaining Wall
FL22 McDougal Littell Science Grade 7
Simulations
EARTH’S WATERSAquifers 66Limits of an Aquifer 79The Ocean Floor 113Ocean Life and Environments 151
EARTH’S SURFACETopographic Maps and Surface Features 215Nuclear Power Plant 315
ELECTRICITY AND MAGNETISMStatic Electricity 339Ohm’s Law 361Circuits 373Electromagnets 409
LIFE OVER TIMEMatching Finch Beaks to Food 487
HUMAN BIOLOGYHuman Body Systems 569Assemble a Skeleton 578
SPACE SCIENCELevels of the Universe 671Sun at Different Wavelengths 780
Visualizations
EARTH’S WATERSThe Water Cycle 53Water Treatment Plant 92Daily Tides 137Life at Hydrothermal Vents 168
EARTH’S SURFACELatitude and Longitude 206Soil Formation 229Chemical Weathering 234Wind Erosion 259Cave Formation 270Hydrogen Fuel Cell 320
ELECTRICITY AND MAGNETISMHard Drive 395Motor 424
LIFE OVER TIMEMolten Rock in Sedimentary Layers 467Fossil Formation 490Response to Environmental Change 534
HUMAN BIOLOGYLung and Diaphragm Movement 597Peristalsis 608Heart Pumping Blood 629Skin Healing 653
SPACE SCIENCENight Sky throughout the Year 676Exploring Seasons 705Lunar Phases 724Virtual Flight through the Solar System 741Shapes of Galaxies 777
Career Centers
Oceanography 41
Mineralogy 189
Music and Computer Science 333
Paleontology 449
Neurobiology 563
Astronomy 665
Internet Resources @ ClassZone.com
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Table of Contents FL23
Resource Centers
NATURE OF SCIENCEResources for the following topics may be found atClassZone.com: Ethics; Prions; Technology and ItsConsequences; Aquifers and Purification.
EARTH’S WATERSResources for the following topics may be found atClassZone.com: Florida’s Coral Reefs; Water; Evidenceof a Water Cycle on Mars; Frozen Fresh Water;Geysers and Hot Springs; Ocean Currents; OceanWaves; Ocean Tides; Ocean Research; Coral Reefs;Hydrothermal Vents; Ocean Pollution and PollutionPrevention.
EARTH’S SURFACEResources for the following topics may be found atClassZone.com: Sinkholes; Satellite Mapping; MapProjections; GIS; Weathering; Soil; Mudflows; Riversand Erosion; Glaciers; Earth System Research; NaturalResources; Pollution-Digesting Microbes; RenewableEnergy Resources.
ELECTRICITY AND MAGNETISMResources for the following topics may be found atClassZone.com: Amusement Park Animatronics;Lightning and Lightning Safety; ElectrochemicalCells; Electrical Safety; Electronics; Electronic andComputer Research; Magnetism; Dams andElectricity; Energy Use and Conservation.
LIFE OVER TIMEResources for the following topics may be found atClassZone.com: Sharks; Evidence of an Event inEarth’s Past; Fossils; Finding the Ages of Rocks; MassExtinctions; Natural Selection; Evidence SupportingEvolution; Current Fossil and Living Fossil Finds;Population Dynamics; Human Population Growth;Introduced Species in the United States.
HUMAN BIOLOGYResources for the following topics may be found at ClassZone.com: Skin and the Sun; Shackleton’sExpedition; Skeletal System; Muscles; RespiratorySystem; Urinary System; Current Medical ImagingTechniques; Circulatory System; Blood Types;Lymphatic System; Skin.
SPACE SCIENCEResources for the following topics may be found atClassZone.com: Cape Canaveral; Telescopes; SpaceExploration; Seasons; Tides; Advances in Astronomy;Impact Craters; Moons of Giant Planets; Life Cyclesof Stars; Galaxies; Galaxy Collisions.
Math Tutorials
NATURE OF SCIENCEBar Graphs 31
EARTH’S WATERSMultiplying Fractions and Whole Numbers 63Volume of a Rectangular Prism 89Coordinates and Line Graphs 123Bar Graphs 160
EARTH’S SURFACESolving Proportions 211Surface Area of a Rectangular Prism 237Making a Line Graph 287Comparing Decimals 312
ELECTRICITY AND MAGNETISMEquations 367Percents and Proportions 388Rounding Decimals 439
LIFE OVER TIMEReading Line Graphs and Multiplying
Whole Numbers 472Writing and Solving Proportions 496Finding the Mean 535
HUMAN BIOLOGYUnit Rates 583Measuring Length 613Making Line Graphs 648
SPACE SCIENCEPowers and Exponents 694Line Graphs 722The Percent Equations 748Scatter Plots 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
Reproducing a Result; Effects of Changes 3
Earth’s Waters
Where Can You See Water? Does the Ice Float? 47
How Much Water Do You Drink? What Happens When Salt Water Evaporates? 79
What Makes Things Float or Sink? How Does Moving Air Affect Water? 113
It’s Alive! Beneath the Surface 151
Earth’s Surface
Earth’s Changing Surface; Using Modern Maps 195
Ice Power; Getting the Dirt on Soil 229Where Has Water Been? How Do
Waves Shape Land? 259Sunlight as an Energy Source; Saving
Water as You Brush 297
Electricity and Magnetism
How Do the Pieces of Tape Interact? Why Does the Water React Differently? 339Will the Flashlight Still Work?
What’s Inside a Calculator? 373Is It Magnetic? How Can You Make
a Chain? 409
Life Over Time
How Do You Know What Happened? How Long Has That Been There? 455
What Can Rocks Show About Earth’s History? Which One of These Things Is Not Like the Others? 487
How Does Population Grow? How Do Populations Differ? 525
Human Biology
How Many Bones Are in Your Hand? How Does It Move? 569
Mirror, Mirror; Water Everywhere 597Blood Pressure; Wet Fingers 629
Space Science
Why Does the Sun Appear to Move AroundEarth? What Colors Are in Sunlight? 671
How Do Shadows Move? What Makes theMoon Bright? 705
How Big Is Jupiter? How Round Is an Orbit? 741How Can Stars Differ? How Do Galaxies
Move Apart? 777
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
Reproducing a ResultUsing only a cup of water and a ping-pong ball, find a way to make the ball float so that it does not touch the cup. Write down your procedure.
Observe and ThinkWhy is it important to keep detailed records of a procedure?
Internet Activity: EthicsGo to ClassZone.com to learn more aboutethics and scientific study.
Observe and ThinkWhat are some of the ethi-cal questions scientistsface? Is there always oneright answer to an ethicalquestion?
NSTA scilinks.org
Solutions Code: MDL069
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Effects of ChangesUse a plastic straw, paper strips, and tapeto make a glider like the oneshown in the photograph.Hold the glider with thesmaller loop of paper infront. Throw the glider sev-eral times and measure howfar it flies. Then, change the sizeof the loops or use different shapesof paper. Test the glider’s flight aftereach change.
Observe and Think How did each change affect the flight of your glider?
• Section Reviews, pp. 14, 25, 33, 38
• Chapter Review, pp. 34-36• FCAT Practice, p. 37
CLASSZONE.COM• Florida Review: Content
Review and FCAT Practice
2 Chapter 1: The Nature of Science
The Natureof Science
All sciences use similarprocesses and tools.
Key Concepts
Basic tools of scienceare universal.Learn why different sciencesshare a common approach.
Scientific ideas arebased on evidence.Learn how different kinds ofscientific inquiries are used togather evidence.
Scientists belong to aworld community.Learn how science and societyinteract with one another.
3SECTION
2SECTION
1SECTION
Growers sometimes spray water onoranges in cold weather. How didthey figure out that this would helpprotect the fruit?
FL24 McDougal Littell Science Grade 7
Nature of Science
Using a Filter 22
Earth’s Waters
Water Moving Underground Design Your Own 72Monitoring Water Quality 98Wave Movement 134Population Sampling 178
Earth’s Surface
Investigate Topographic Maps 216Testing Soil 246Creating Stream Features 272Wind Power 322
Electricity and Magnetism
Lightning 358Design an Electronic
Communication Device Design Your Own 398Build a Speaker 432
Life Over Time
Geologic Time 480Modeling Natural Selection 506Sustainable Resource Management 552
Human Biology
A Closer Look at Muscles 590Modeling a Kidney 618Heart Rate and Exercise 638
Space Science
Observing Spectra 684Modeling Seasons 714Exploring Impact Craters Design Your Own 770Temperature, Brightness, and Color 784
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.
Measure 30 mL of clean water. Pour the waterinto one of the cups. Use the marker to mark thelevel on the masking tape.Repeat so that all of thecups are marked at 30mL. Label your cupsA–F.
Pour 100 mL of cleanwater into one ofyour filters. Discard thefiltered water.
Pour 50 mL of clean water into one of the filtersso that it empties into cup A. Record the time ittakes for 30 mL to run through the filter.Observe the water and filter.
Repeat step 5 two times using dirty water.
Repeat steps 4–6 using your second filter andcups D–F.
1. RECORD Make sure you have recorded allthe measurements and observations in yourscience notebook.
2. OBSERVE Which filter removed the mostimpurities? What characteristics are you usingto describe the water? Through which filterdid water flow faster?
3. INTERPRET What was the purpose ofpouring clean water through the filters instep 5?
4. IDENTIFY VARIABLES List the independent variable and the two dependent variables.
1. COMPARE Which filter was the mosteffective? Present your evidence. How did the filters differ in terms of the two depen-dent variables?
2. EVALUATE Were the trials of each filterconsistent? If not, explain what changed.
3. APPLY Suppose you want to design a filterto clean the water in a fish tank. How wouldthis filter differ from the ones that you test-ed?
CHALLENGE Particles settle to the bottom ofliquids over time. Alum is a material that bindsvery small particles together in a liquid and helpsthem settle. Add 1 mL of alum to 50 mL of dirtywater. Set up a control sample with no alum. Stirthe samples and then observe them after 10–15minutes. How could alum help your filteringexperiment?
INVESTIGATE Further
ConcludeWriteIt Up
Observe and AnalyzeWriteIt Up
Using A Filter
Observe and Analyze
Table 1. Filtering Test Results
Chapter 1: The Nature of Science 23
Filter Material Cup
Control (A)
Trial 1 (B)
Trial 2 (C)
Control (E)
Trial 1 (F)
Trial 2 (G)
Time (sec) Observations
CHAPTER INVESTIGATIONCHAPTER INVESTIGATION
22 Chapter 1: The Nature of Science
MATERIALS• clean water• contaminants such as:
soil, vinegar, vegetableoil, food coloring, dry leaves
• 1 L container• stirrers• 8 clear cups• 50 mL beaker• masking tape and marker• 2 funnels• coffee filters• rubber bands• pieces of cloth• coarse sand• charcoal• stopwatchChallenge Materials• alum• 2 clear cups
Using a FilterOVERVIEW AND PURPOSE Using variables in a controlled experiment can help you determine many things. For example, the effectiveness of a filter to clean water dependson the type of filter that is used and the condition of the water.By testing different filters and gathering evidence you can deter-mine which filter is the most effective. Keep in mind that thatthe independent variable is the factor that you wish to test andthe dependent variable is what you measure to determine yourresults. In this investigation you will
• make water dirty and try to clean it• identify the variables
Which filter is the most effective?
Work with a partner. Decide which contaminants to add to your clean water. Measure and record the amount of eachingredient that you use. Mix your water thoroughly in a largecontainer. You should make at least 1 L of dirty water.
Choose two of the following filters and set them up.
• filter paper Line your funnel with a coffee filter.• cloth Line a funnel with a piece of cloth.• sand Use a rubber band to secure a piece of cloth around
the bottom of the funnel, which will hold the sand.Choose and measure an amount of sand and pour it intothe funnel.
• charcoal Follow the procedure for sand except use charcoal.• other Combine any of the materials and ideas listed
above to design your own filter. Record what you use to make the filter.
Procedure
ProblemWriteIt Up
Table of Contents FL25
Nature of Science
Observations and Opinions 5Effects of Changes in Procedures 14
Earth’s Waters
Water Vapor 49Water Collection 56Flow of Water 64Concentration 90The Value of Fresh Water 100Density 115Currents 124Waves 129Air Bladders 161Ocean Pollution 170
Earth’s Surface
Mapping 203Topographic Maps 212Mechanical Weathering 231Soil Composition 238Divides 266Glaciers 281Energy Use 308Nuclear Energy 313
Electricity and Magnetism
Static Electricity 341Static Discharge 350Current 360Circuits 375Codes 389Magnetism 411Magnetism from Electric Current 420Energy Conversion 427
Life Over Time
Rocks 457Time Scales 473Fossils 489Evidence 508Population Density 536Population Change 544
Human Biology
Levers 576Muscles 584Breathing 599Digestion 607Waste Removal 614The Circulatory System 631Membranes 640The Skin 649
Space Science
Distance 673Distortion of Light 679Viewing Space Objects 686Time Zones 707The Moon’s Motion 716Planet Formation 743Surfaces 749Solar Atmosphere 779Characteristics of Stars 786The Milky Way 794Large Numbers 799
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 way to study the natural world.People continually ask questions, explore ideas, and reach conclusions.Sometimes scientific methods can help them, but not all questions canbe answered scientifically. For example, suppose people are decidingwhich musicians to invite to perform in the town’s park. They mightdiscuss their opinions vigorously, but science cannot help them makethe best choice.
What can be studied scientifically? Anything that can be observedobjectively and involves features of the natural world. Objective obser-vations are the same for everyone. For example, choosing the best typeof grass to plant in the park can be approached scientifically. People cantest varieties of grass to find out which would grow well in the parkand withstand being walked on by large numbers of concert-goers.The grasses are part of the natural world, their growth can be tested,and different observers will get similar results.
VOCABULARY
scientific processes p. 4hypothesis p. 5creative thinking p. 6skepticism p. 7critical thinking p. 8
BEFORE, you learned
• Science collect evidence bymaking observations.
• Scientific results must be repro-ducible.
• Scientists record and shareresults.
NOW, you will learn
• How people use scientific pro-cesses
• About scientific habits of mind• How scientists build up scientific
information
KEY CONCEPT
Basic tools of science are universal.
Sunshine StateSTANDARDSSC.H.1.3.2: The studentknows that the study ofthe events that led sci-entists to discoveriescan provide informationabout the inquiry pro-cess and its effects.SC.H.1.3.3: The studentknows that science disci-plines differ from oneanother in topic, tech-niques, and outcomes,but that they share acommon purpose, phi-losophy, and enterprise.SC.H.1.3.6: The studentrecognizes the scientificcontributions that aremade by individuals ofdiverse backgrounds,interests, talents, andmotivations.
MATERIALS• 3 bottles with lids• water• spoon• 3 types of
cleaning products
EXPLORE Observations and Opinions
How are observations different from opinions?
PROCEDURE
Fill the bottles one-third full with water.
Add one spoonful of a different type of cleaning product to each bottle. Fasten the lidstightly and shake each bottle for 15 seconds.
Observe the suds in each bottle.
WHAT DO YOU THINK?How is comparing the height of suds produced by each cleaning product different from comparing how good they smell?
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1
FL26 McDougal Littell Science Grade 7
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
Solving Problems Design Your Own 9Ethics Judging 28
Earth’s Waters
The Water Cycle Design Your Own 52Icebergs Calculating 61Aquifer Filtration Making Models 67Water Usage Analyzing Data 83Water Conservation Measuring 103Density Predicting 118Currents Observing 127Tides Making Models 138Coastal Environments Design Your Own 156Floating Design Your Own 165
Earth’s Surface
Geosphere’s Layers Modeling 201Map Projections Modeling 208Satellite Imaging Modeling 220Chemical Weathering Identifying Variables 234Soil Conservation Making Models 251Erosion Design Your Own 262Longshore Drift Observing 276Kettle Lake Formation Design Your Own 285Fossil Fuels Modeling 305Conservation Design Your Own 310
Electricity and Magnetism
Making a Static Detector Inferring 346Conductors and Insulators Interpreting Data 354Electric Cells Inferring 363Fuses Making Models 380Circuits Inferring 386
Digital Information Making Models 391Earth’s Magnetic Field Inferring 417Electromagnets Observing 422Electric Current Inferring 430Power Making Models 437
Life Over Time
Learning from Tree Rings Observing 462Relative and Absolute Age Making Models 468Fossil Records Analyzing 491Genes Sequencing 513Limiting Factors Design Your Own 540Population Graphing data 548
Human Biology
Systems Predicting 572Movable Joints Observing 581Lungs Making models 601Chemical Digestion Making models 609Antibodies Making models 645Skin Protection Observing 651
Space Science
Constellation Positions Analyzing 677Launch Planning Identifying Variables 689Weathering Predicting 697Rotation Making Models 708Moon Features Inferring 719Phases of the Moon Making Models 726Distances Using Models 746Layers Using Models 752Giant Planets Observing 761Parallax Measuring 787Galaxy Shapes Classifying 795Galaxies Measuring 802
I-AheadI-Ahead
Use the guided template
at www.publisher.com
How does water cycle through anenvironment?PROCEDURE
Construct an environment in a jar with a lid. You can use plants, soil, water, and containers.
Find the mass of your closed jar after you construct it.
Draw a detailed, colored picture of your jar.
Let your jar sit for several days.
Find the mass of your jar again, and draw another picture of it.
WHAT DO YOU THINK?• How did the jar’s appearance change over several days?
• How did its mass change?
• What can you conclude about how water cycles through an environment?
CHALLENGE How could you change your environment so that the jar’s appearance would change at a faster rate?
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The Water CycleThe Water CycleSKILL FOCUSModeling
MATERIALS• jar with lid• soil• rocks or pebbles• sand• smaller
containers• water• small plants• triple-beam
balance
TIME30 minutes (for construction;20 minutes foranalysis)
Water moves in a worldwide cycle.Water continually moves and changes form. Water from clouds fallsover the oceans and on land. Water flows in rivers and collects in lakesand under the ground. Water can be a solid in the form of ice, or itcan be an invisible vapor in the atmosphere.
The Water CycleWater’s movement on Earth is a cycle, or continually repeating process.The is the continuous movement of water through theenvironment of Earth. In the water cycle, water is constantly changingform, from a liquid on land, to a vapor in the atmosphere, and againto a liquid that falls to the surface. The flow of water on land andunderground is also part of the water cycle. As water moves in thewater cycle, the total amount of water in Earth’s system does notchange very much. The water cycle involves three major processes:evaporation, condensation, and precipitation.
water cycle
52 Unit 1: Earth’s Waters
MAIN IDEA AND DETAILSRecord in your notes thismain idea and importantdetails about the watercycle.
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