Sách cambrige science khối 6 level red national georaphic, Sách cambrige science khối 6 level red national georaphic, Sách cambrige science khối 6 level red national georaphic Sách cambrige science khối 6 level red national georaphic
Trang 3Level Red
The cover shows the Colorado
River in the Grand Canyon
It is the primary river of the
American Southwest This
forked lightning bolt shows a
large static discharge between
the dark clouds and the ground
This red-eyed tree frog can be
found in rain forests in South
and Central America, and as far
of the publisher.
The National Geographic features were designed and developed by the National Geographic Society’s Education Division Copyright © National Geographic Society.The name “National Geographic Society” and the Yellow Border Rectangle are trademarks of the Society, and their use, without prior written permission, is strictly prohibited.
The “Science and Society” and the “Science and History” features that appear in this book were designed and developed by TIME School Publishing, a division of TIME Magazine.TIME and the red border are trademarks of Time Inc All rights reserved.
Trang 4The Nature of Matter 2
Chapter 1 The Nature of Science 4
Chapter 2 Measurement 40
Chapter 3 Matter and Its Changes 68
Chapter 4 Atoms, Elements, and the Periodic Table 96
Interactions of Matter 126
Chapter 5 Motion, Forces, and Simple Machines 128
Chapter 6 Energy 160
Chapter 7 Electricity and Magnetism 192
Chapter 8 Waves 224
Earth’s Changing Surface 252
Chapter 9 Rocks and Minerals 254
Chapter 10 Forces Shaping Earth 286
Chapter 11 Weathering and Erosion 314
Chapter 12 The Atmosphere in Motion 340
Chapter 13 Oceans 372
Beyond Earth 404
Chapter 14 Exploring Space 406
Chapter 15 The Solar System and Beyond 438
Life’s Diversity 472
Chapter 16 Cells—The Units of Life 474
Chapter 17 Invertebrate Animals 496
Chapter 18 Vertebrate Animals 528
Chapter 19 The Human Body 558
Chapter 20 The Role of Genes in Inheritance 588
Life and the Environment 614
Chapter 21 Ecology 616
Chapter 22 Earth’s Resources 644
Contents
In Brief
Trang 5Alton J Banks, PhD
Director of the Faculty Center for Teaching and Learning North Carolina State University
Jerome A Jackson, PhD
Whitaker Eminent Scholar in Science
Program Director Center for Science, Mathematics, and Technology Education Florida Gulf Coast University Fort Meyers, FL
William C Keel, PhD
Department of Physics and Astronomy University of Alabama Tuscaloosa, AL
New York, NY
Authors
Series Consultants
Education Division Washington, D.C.
Alton BiggsRetired Biology Teacher Allen High School Allen, TXLucy Daniel, PhDTeacher/Consultant Rutherford County Schools Rutherfordton, NCRalph M Feather Jr., PhD
Assistant Professor Geoscience Department Indiana University of Pennsylvania
Indiana, PA
Edward OrtlebScience Consultant
St Louis, MOSusan Leach SnyderRetired Teacher, Consultant Jones Middle School Upper Arlington, OHDinah ZikeEducational Consultant Dinah-Might Activities, Inc.
San Antonio, TX
Trang 6Dominic Salinas, PhD
Middle School Science Supervisor Caddo Parish Schools Shreveport, LA
Cheryl Wistrom
St Joseph’s College Rensselaer, IN
Carl Zorn, PhD
Staff Scientist Jefferson Laboratory Newport News, VA
MATH
Michael Hopper, DEng
Manager of Aircraft Certification L-3 Communications Greenville, TX
Teri Willard, EdD
Mathematics Curriculum Writer
Barry Barto
Special Education Teacher John F Kennedy Elementary Manistee, MI
Carol A Senf, PhD
School of Literature, Communication, and Culture Georgia Institute of Technology
Atlanta, GA
Rachel Swaters-Kissinger
Science Teacher John Boise Middle School Warsaw, MO
SAFETY
Aileen Duc, PhD
Science 8 Teacher Hendrick Middle School, Plano ISD
Plano, TX
Sandra West, PhD
Department of Biology Texas State University-San Marcos
San Marcos, TX
ACTIVITY TESTERS
Nerma Coats Henderson
Pickerington Lakeview Jr High
School Pickerington, OH
Mary Helen Mariscal-Cholka
William D Slider Middle School
Trang 7Anthony J DiSipio, Jr.
8th Grade Science Octorana Middle School Atglen, PA
George Gabb
Great Bridge Middle School Chesapeake Public Schools Chesapeake, VA
Annette D’Urso Garcia
Kearney Middle School Commerce City, CO
Nerma Coats Henderson
Pickerington Lakeview Jr.
High School Pickerington, OH
Burke, VA
Michael Mansour
Board Member National Middle Level Science Teacher’s Association John Page Middle School Madison Heights, MI
Mary Helen Mariscal-Cholka
William D Slider Middle School
Norma Neely, EdD
Associate Director for Regional
Projects Texas Rural Systemic Initiative
Austin, TX
Annette Parrott
Lakeside High School Atlanta, GA
Nora M Prestinari Burchett
Saint Luke School McLean, VA
Trang 8on the content and design of the Student Edition They provided valuable input in the
development of the 2005 edition of Glencoe Science Level Red.
Teacher Advisory Board
The Glencoe middle school science Student Advisory Board taking a timeout at COSI,
a science museum in Columbus, Ohio.
on the design of the Student Edition We thank these students for their hard work and
creative suggestions in making the 2005 edition of Glencoe Science Level Red student
Trang 9Why do I need
my science book?
Have you ever been in class and
not understood all of what was
presented? Or, you understood
everything in class, but at home,
got stuck on how to answer a
question? Maybe you just
wondered when you were ever
going to use this stuff?
These next few pages
are designed to help you
understand everything your
science book can be used
for besides a paperweight!
Before You Read
● Chapter Opener Science is occurring all around you,and the opening photo of each chapter will preview the
science you will be learning about The Chapter
Preview will give you an idea of what you will be
learning about, and you can try the Launch Lab to
help get your brain headed in the right direction The
Foldables exercise is a fun way to keep you organized.
● Section Opener Chapters are divided into two to four
sections The As You Read in the margin of the first
page of each section will let you know what is mostimportant in the section It is divided into four parts
What You’ll Learn will tell you the major topics you
will be covering Why It’s Important will remind you
why you are studying this in the first place! The
Review Vocabulary word is a word you already know,
either from your science studies or your prior
knowl-edge The New Vocabulary words are words that you
need to learn to understand this section These words
will be in boldfaced print and highlighted in the
section Make a note to yourself to recognize thesewords as you are reading the section
Trang 10As You Read
● Headings Each section has a title
in large red letters, and is furtherdivided into blue titles andsmall red titles at the begin-nings of some paragraphs
To help you study, make anoutline of the headings andsubheadings
● Margins In the margins ofyour text, you will find many helpful
resources The Science Online exercises and
Integrate activities help you explore the topics
you are studying MiniLabs reinforce the
sci-ence concepts you have learned
● Building Skills You also will find an
Applying Math or Applying Science activity
in each chapter This gives you extra tice using your new knowledge, and helpsprepare you for standardized tests
prac-● Student Resources At the end of the book
you will find Student Resources to help you
throughout your studies These include
Science, Technology, and Math Skill books, an English/Spanish Glossary, and an Index Also, use your Foldables as a resource.
Hand-It will help you organize information, andreview before a test
● In Class Remember, you can always
ask your teacher to explain anything you don’t understand
Science Vocabulary Make the following Foldable to help you understand the vocabulary terms in this chapter.
Fold a vertical sheet of notebook paper from side to side.
Cut along every third line of only the top layer to form tabs.
Label each tab with a vocabulary word from the chapter.
Build Vocabulary As you read the chapter, list the vocabulary words on the tabs As you learn the definitions, write them under the tab for each vocabulary word.
STEP 3
STEP 2 STEP 1
ix
Look For
At the beginning of every section
Trang 11In Lab
Working in the laboratory is one of the best ways to understand the cepts you are studying Your book will be your guide through your laboratoryexperiences, and help you begin to think like a scientist In it, you not only willfind the steps necessary to follow the investigations, but you also will findhelpful tips to make the most of your time
con-● Each lab provides you with a Real-World Question to remind you that
science is something you use every day, not just in class This may lead
to many more questions about how things happen in your world
● Remember, experiments do not always produce the result you expect
Scientists have made many discoveries based on investigations with pected results You can try the experiment again to make sure your resultswere accurate, or perhaps form a new hypothesis to test
unex-● Keeping a Science Journal is how scientists keep accurate records of
obser-vations and data In your journal, you also can write any questions thatmay arise during your investigation This is a great method of remindingyourself to find the answers later
Look For
● Launch Labsstart every chapter.
● MiniLabsin the margin of each
chapter
● Two Full-Period Labs
in everychapter
● EXTRA Try at Home Labs
at the
end of your book
● the Web sitewith
laboratory
demonstrations.
Trang 12Before a Test
Admit it! You don’t like to take tests! However, there are
ways to review that make them less painful Your book willhelp you be more successful taking tests if you use theresources provided to you
● Review all of the New Vocabulary words and be sure you
understand their definitions
● Review the notes you’ve taken on your Foldables, in class,
and in lab Write down any question that you still needanswered
● Review the Summaries and Self Check questions at the
end of each section
● Study the concepts presented in the chapter by reading
the Study Guide and answering the questions in the Chapter Review.
● the Study Guideand Review
at the end of each chapter
● the Standardized Test Practice
after each chapter
Trang 13Let’s Get Started
To help you find the information you need quickly, use the Scavenger Hunt below to learn where things are located in Chapter 1.
What is the title of this chapter?
What will you learn in Section 1?
Sometimes you may ask, “Why am I learning this?” State a reason why the concepts from Section 2 are important
What is the main topic presented in Section 2?
How many reading checks are in Section 1?
What is the Web address where you can find extra information?
What is the main heading above the sixth paragraph in Section 2?
There is an integration with another subject mentioned in one of the margins
of the chapter What subject is it?
List the new vocabulary words presented in Section 2
List the safety symbols presented in the first Lab
Where would you find a Self Check to be sure you understand the section?
Suppose you’re doing the Self Check and you have a question about concept mapping Where could you find help?
On what pages are the Chapter Study Guide and Chapter Review?
Look in the Table of Contents to find out on which page Section 2 of the chapter begins
You complete the Chapter Review to study for your chapter test
Where could you find another quiz for more practice?
Trang 14Contents
In each chapter, look for these opportunities for review and assessment:
• Reading Checks
• Caption Questions
• Section Review
• Chapter Study Guide
• Chapter Review
• Standardized Test Practice
• Online practice at
red.msscience.com
The Nature of Matter—2
The Nature of Science—4
Section 1 What is science? 6
Section 2 Science in Action 12
Section 3 Models in Science 21
Section 4 Evaluating Scientific Explanation 27
Lab What is the right answer? 31
Lab Identifying Parts of an Investigation 32
Measurement—40 Section 1 Description and Measurement 42
Section 2 SI Units 50
Lab Scale Drawing 55
Section 3 Drawings, Tables, and Graphs 56
Lab: Design Your Own Pace Yourself 60
Matter and its Changes—68 Section 1 Physical Properties and Changes 70
Section 2 Chemical Properties and Changes 80
Lab Liquid Layers 87
Lab: Design Your Own Fruit Salad Favorites 88
Atoms, Elements, and the Periodic Table—96 Section 1 Structure of Matter 98
Section 2 The Simplest Matter 106
Lab Elements and the Periodic Table 112
Section 3 Compounds and Mixtures 113
Lab Mystery Mixture 118
Trang 15Interactions of Matter—126
Motion, Forces, and Simple Machines—128
Section 1 Motion 130
Section 2 Newton’s Laws of Motion 136
Section 3 Work and Simple Machines 144
Lab Motion 151
Lab: Use the Internet Methods of Travel 152
Energy—160 Section 1 Energy Changes 162
Section 2 Temperature 170
Section 3 Chemical Energy 178
Lab Converting Potential and Kinetic Energy 183 Lab Comparing Temperature Changes 184
Electricity and Magnetism—192 Section 1 Electric Charge and Forces 194
Section 2 Electric Current 201
Section 3 Magnetism 209
Lab Batteries in Series and Parallel 215
Lab Magnets and Electric Current 216
Waves—224 Section 1 What are waves? 226
Section 2 Wave Properties 231
Lab Waves on a Spring 236
Section 3 Wave Behavior 237
Lab: Design Your Own
In each chapter, look for these opportunities for review and assessment:
• Reading Checks
• Caption Questions
• Section Review
• Chapter Study Guide
• Chapter Review
• Standardized Test Practice
• Online practice at
red.msscience.com
Trang 16xv
Earth’s Changing Surface—252
Rocks and Minerals—254
Section 1 Minerals—Earth’s Jewels 256
Section 2 Igneous and Sedimentary Rocks 265
Section 3 Metamorphic Rocks and the Rock Cycle 272
Lab Gneiss Rice 277
Lab Classifying Materials 278
Forces Shaping Earth—286 Section 1 Earth’s Moving Plates 288
Lab Earth’s Moving Plates 298
Section 2 Uplift of Earth’s Crust 299
Lab: Model and Invent Isostasy 306
Weathering and Erosion—314 Section 1 Weathering and Soil Formation 316
Lab Classifying Soils 322
Section 2 Erosion of Earth’s Surface 323
Lab: Design Your Own Measuring Soil Erosion 332
The Atmosphere in Motion—340 Section 1 The Atmosphere 342
Section 2 Earth’s Weather 348
Section 3 Air Masses and Fronts 356
Lab Interpreting Satellite Images 363
Lab: Design Your Own Creating Your Own Weather Station 364
Trang 17Oceans—372
Section 1 Ocean Water 374
Lab Desalination 379
Section 2 Ocean Currents and Climate 380
Section 3 Waves 385
Section 4 Life in the Oceans 389
Lab: Model and Invent Waves and Tides 396
Beyond Earth—404 Exploring Space—406 Section 1 Radiation from Space 408
Lab Building a Reflecting Telescope 414
Section 2 Early Space Missions 415
Section 3 Current and Future Space Missions 423
Lab: Use the Internet Star Sightings 430
The Solar System and Beyond—438 Section 1 Earth’s Place in Space 440
Lab Moon Phases 447
Section 2 The Solar System 448
Section 3 Stars and Galaxies 456
Lab: Design Your Own Space Colony 464
In each chapter, look for these opportunities for review and assessment:
• Reading Checks
• Caption Questions
• Section Review
• Chapter Study Guide
• Chapter Review
• Standardized Test Practice
• Online practice at
red.msscience.com
Trang 18Contents
Life’s Diversity—472
Cells–The Units of Life—474
Section 1 The World of Cells 476
Lab Observing Algae 482
Section 2 The Different Jobs of Cells 483
Lab: Design Your Own Water Movement in Plants 488
Invertebrate Animals—496 Section 1 What is an animal? 498
Section 2 Sponges, Cnidarians, Flatworms, and Roundworms 501
Section 3 Mollusks and Segmented Worms 506
Section 4 Arthropods and Echinoderms 512
Lab Observing Complete Metamorphosis 519
Lab: Design Your Own Garbage-Eating Worms 520
Vertebrate Animals—528 Section 1 Chordate Animals 530
Section 2 Amphibians and Reptiles 535
Lab Frog Metamorphosis 540
Section 3 Birds 541
Section 4 Mammals 545
Lab: Model and Invent Homes for Endangered Animals 550
The Human Body—558 Section 1 Body Systems 560
Lab Improving Reaction Time 573
Section 2 Human Reproduction 574
Lab: Design Your Own Defensive Saliva 580
Trang 19The Role of Genes in Inheritance—588
Section 1 Continuing Life 590
Lab Getting DNA from Onion Cells 598
Section 2 Genetics—The Study of Inheritance 599
Lab: Use the Internet Genetic Traits: The Unique You 606
Life and the Environment—614 Ecology—616 Section 1 What is an ecosystem? 618
Lab Ecosystem in a Bottle 626
Section 2 Relationships Among Living Things 627
Section 3 Energy Through the Ecosystem 633
Lab: Design Your Own What’s the limit? 636
Earth’s Resources—644 Section 1 Natural Resource Use 646
Lab Using Water 654
Section 2 People and the Environment 655
Section 3 Protecting the Environment 663
Lab: Design Your Own Using Land 668
In each chapter, look for these opportunities for review and assessment:
• Reading Checks
• Caption Questions
• Section Review
• Chapter Study Guide
• Chapter Review
• Standardized Test Practice
• Online practice at
red.msscience.com
Trang 20Contents
Student Resources—676
Science Skill Handbook—678
Scientific Methods 678
Safety Symbols 687
Safety in the Science Laboratory 688
Extra Try at Home Labs—690 Technology Skill Handbook—701 Computer Skills 701
Presentation Skills 704
Math Skill Handbook—705 Math Review 705
Science Applications 715
Reference Handbooks—720 Periodic Table of the Elements 720
Topographic Map Symbols 722
Rocks 723
Minerals 724
Diversity of Life: Classification of Living Organisms 726
Use and Care of a Microscope 730
English/Spanish Glossary—731 Index—750
Credits—769
Trang 21Cross-Curricular Readings
Unit Openers
Unit 1 How are Arms and Centimeters Connected? 2
Unit 2 How are Train Schedules and Oil Pumps Connected? 126
Unit 3 How are Rocks and Fluorescent Lights Connected? 252
Unit 4 How are the Inuit and Astronauts Connected? 404
Unit 5 How are Animals and Airplanes Connected? 472
Unit 6 How are Oatmeal and Carpets Connected? 614
VISUALIZING 1 The Modeling of King Tut 24
2 Precision and Accuracy 46
3 Dichotomous Keys 78
4 The Periodic Table 108
5 Newton’s Laws and Space Travel 142
6 Kinetic Energy 165
7 Batteries 206
8 Interference 242
9 Igneous Rock Features 268
10 Rift Valleys 294
11 Mass Movements 324
12 The Water Cycle 346
13 Food Chains in a Food Web 393
14 Space Probes 419
15 Galaxies 460
16 Life’s Organization 486
17 Arthropod Diversity 514–515 18 Fish Diversity 533
19 Vitamins 565
20 Human Reproduction 596
21 Biotic Factors 621
Trang 226 “Hiroshima” 186
Trang 2311 Water’s Force 315
available as a video lab
Trang 243 Observing Yeast 84
Trang 26Content Details
2 Pace Yourself 60–61
The Unique You 606–607
Use the Internet Labs Model and Invent Labs Design Your Own Labs Two-Page Labs
Trang 2716 Red Blood Cells 485
20 Alleles in Sex Cells 603
22 Reusing Plastic 665
Applying Science Applying Math
Trang 28Standardized Test Practice
Trang 30Visit to find project ideas and resources.
Projects include:
• History Brainstorm characteristics of science fields, and then design a collage with science ideas for a ceiling tile or book cover.
• Technology Convert a family recipe from English measurement to SI units
of measurement Enjoy a classroom bake-off!
• Model Create a character in an SI world Develop a picture storybook or comic book to demonstrate your knowledge of SI measurement.
The Nature of Science: Evaluating Bias in Advertisementshelps students to become informed about the techniques of advertising and evaluate bias in print media.
red.msscience.com/unit_project
About 5,000 years ago, the Egyptians developed one of the earliest recorded units of measurement—the cubit, which was based on the length of the arm from elbow to fingertip The Egyptian measurement system probably influenced later systems, many of which also were based on body parts such as arms and feet Such systems, however, could be problematic, since arms and feet vary in length from one person to another Moreover, each country had its own system, which made it hard for people from different countries to share information The need for a precise, universal measurement system eventually led to the adoption
of the meter as the basic international unit of length A meter is defined as the distance that light travels in a vacuum in a certain fraction of a second—a distance that never varies Meters are divided into smaller units called centimeters, which are seen on the rulers here.
3
Trang 311 What is science?
2 Science in Action
3 Models in Science
4 Evaluating Scientific Explanation
Lab What is the right answer?
Lab Identifying Parts of an Investigation
Virtual Lab How is a controlled
experiment performed?
How is science a par t
of your ever yday life?
Scientists studying desert ecosystems inCalifornia wondered how such a dry environ-ment could produce such beautiful, prolificflowers Scientists began asking questions andperforming investigations
Write down three examples ofscience in your everyday life
Science Journal
The Nature
of Science
Trang 32Science Make the following Foldable to help identify what you already know, what you want to know, and what you learned about science.
Fold a vertical sheet
of paper from side to side Make the front edge about 1/2 inch shorter than the back edge.
Turn lengthwise and fold into thirds.
Unfold and cut only the top layer along both folds to make three tabs Label each tab.
Identify Questions Before you read the ter, write what you already know about science under the left tab of your Foldable, and write questions about what you’d like to know under the center tab After you read the chapter, list what you learned under the right tab.
chap-STEP 3 STEP 2
in action scientists can study nature
Perform the lab below to see how gravityaffects objects
1. Collect three identical, unsharpenedpencils
2. Tape two of the pencils together
3. Hold all the pencils at the same height ashigh as you can Drop them together andobserve what happens as they fall
4 Think Critically Did the single pencil fallfaster or slower than the pair? Predict inyour Science Journal what would happen
if you taped 30 pencils together anddropped them at the same time as youdropped a single pencil
Trang 33Learning About the World
When you think of a scientist, do you imagine a person in alaboratory surrounded by charts, graphs, glass bottles, and bub-bling test tubes? It might surprise you to learn that anyone whotries to learn something about the natural world is a scientist
Science is a way of learning more about the natural world.
Scientists want to know why, how, or when something occurred.This learning process usually begins by keeping your eyes openand asking questions about what you see
Asking Questions Scientists ask many questions How dothings work? What do things look like? What are they made of?Why does something take place? Science can attempt to answermany questions about the natural world, but some questions can-
Who should you vote for? What does this poem mean? Who isyour best friend? Questions about art, politics, personal prefer-ence, or morality can’t be answered by science Science can’t tellyou what is right, wrong, good, or bad
What is science?
■ Definescience and identify
ques-tions that science cannot answer.
■ Compareand contrast theories
Science can be used to learn more
about the world you live in.
Review Vocabulary
theory: explanation of things or
events that is based on
knowl-edge gained from many
observa-tions and experiments
New Vocabulary
•science •life science
•scientific •Earth science
theory •physical
•scientific law science
•system •technology
Figure 1 Questions
about politics, literature,
and art cannot be answered
by science.
Trang 34SECTION 1 What is science? 7
Question
Possible outcomes
One explanation
Explanation still possible
Explanation modified
Explanation discarded
New possible explanation
New information
Figure 2 As new information becomes available, explanations can be modified or discarded and new explanations can be made
Possible Explanations If learning about your world beginswith asking questions, can science provide answers to thesequestions? Science can answer a question only with the informa-tion available at the time Any answer is uncertain because peo-ple will never know everything about the world around them
With new knowledge, they might realize that some of the oldexplanations no longer fit the new information As shown in
Figure 2,some observations might force scientists to look at oldideas and think of new explanations Science can only providepossible explanations
Why can’t science answer questions with certainty?
Scientific Theories An attempt to explain a pattern
observed repeatedly in the natural world is called a scientific
theory Theories are not simply guesses or someone’s opinions,
nor are theories vague ideas Theories in science must be ported by observations and results from many investigations
sup-They are the best explanations that have been found so far
However, theories can change As new data become available,scientists evaluate how the new data fit the theory If enoughnew data do not support the theory, the theory can be changed
to fit the new observations better
Scientific Laws A rule that describes a pattern in nature is a
scientific law For an observation to become a scientific law, it
must be observed repeatedly The law then stands until someonemakes observations that do not follow the law A law helps youpredict that an apple dropped from arm’s length will always fall
to Earth The law, however, does not explain why gravity exists
or how it works A law, unlike a theory, does not attempt toexplain why something happens It simply describes a pattern
Trang 35Systems in Science
Scientists can study many different things in nature Somemight study how the human body works or how planets movearound the Sun Others might study the energy carried in a light-ning bolt What do all of these things have in common? All of
them are systems A system is a collection of structures, cycles,
and processes that relate to and interact with each other Thestructures, cycles, and processes are the parts of a system, just likeyour stomach is one of the structures of your digestive system
What is a system?
Systems are not found just in science Your school is a systemwith structures such as the school building, the tables andchairs, you, your teacher, the school bell, your pencil, and many
school day also has cycles Your daily class schedule and the endar of holidays are examples of cycles Many processes are atwork during the school day When you take a test, your teacherhas a process You might be asked to put your books and papersaway and get out a pencil before the test is distributed When thetime is over, you are told to put your pencil down and pass yourtest to the front of the room
cal-Parts of a System Interact In a system, structures, cycles,and processes interact Your daily schedule influences where you
go and what time you go The clock shows the teacher when thetest is complete, and you couldn’t complete the test without apencil
Figure 3 Systems are a
collection of structures, cycles,
and processes.
Infer What systems can you
identify in this classroom?
Classifying Parts
of a System
Procedure
Think about how your school’s
cafeteria is run Consider the
physical structure of the
cafe-teria How many people run
it? Where does the food come
from? How is it prepared?
Where does it go? What other
parts of the cafeteria system
are necessary?
Analysis
Classify the parts of your
school cafeteria’s system as
structures, cycles,
or processes.
Trang 36SECTION 1 What is science? 9
Parts of a Whole All systems are made up of other systems
For example, you are part of your school The human body is asystem—within your body are other systems Your school is part
of a system—district, state, and national You have your regionalschool district Your district is part of a statewide school system
Scientists often break down problems by studying just one part
of a system A scientist might want to learn about how tion of buildings affects the ecosystem Because an ecosystemhas many parts, one scientist might study a particular animal,and another might study the effect of construction on plant life
construc-The Branches of Science
Science often is divided into three main categories, orbranches—life science, Earth science, and physical science Eachbranch asks questions about different kinds of systems
Life Science The study of living systems and the ways in
which they interact is called life science Life scientists attempt
to answer questions like “How do whales navigate the ocean?”
and “How do vaccines prevent disease?” Life scientists can studyliving organisms, where they live, and how they interact Dian
habitat, and their behaviors
People who work in the health field know a lot about the lifesciences Physicians, nurses, physical therapists, dietitians, medicalresearchers, and others focus on the systems of the human body
Some other examples of careers that use life science include ogists, zookeepers, botanists, farmers, and beekeepers
biol-Figure 4 Over a span of
18 years, life scientist Dian Fossey spent much of her time observing mountain gorillas in Rwanda, Africa She was able to interact with them as she learned about their behavior.
Health Integration Systems The human body
is composed of many ent systems that all inter-act with one another toperform a function Theheart is like the controlcenter Even though not allsystems report directly tothe heart, they all interactwith its function If theheart is not working, theother systems fail as well.Research human body sys-tems and explain how onesystem can affect another
Trang 37differ-Figure 5 These volcanologists
are studying the temperature of
the lava flowing from a volcano.
Earth Science The study of Earth systems and the systems in
space is Earth science It includes the study of nonliving things
such as rocks, soil, clouds, rivers, oceans, planets, stars, meteors,and black holes Earth science also covers the weather and cli-mate systems that affect Earth Earth scientists ask questions like
“How can an earthquake be detected?” or “Is water found onother planets?” They make maps and investigate how geologicfeatures formed on land and in the oceans They also use theirknowledge to search for fuels and minerals Meteorologists studyweather and climate Geologists study rocks and geologic fea-
vol-canoes—measuring the temperature of lava
What do Earth scientists study?
Physical Science The study of matter and energy is
physical science Matter is anything that takes up space and
has mass The ability to cause change in matter is energy.Living and nonliving systems are made of matter Examplesinclude plants, animals, rocks, the atmosphere, and the water
in oceans, lakes, and rivers Physical science can be dividedinto two general fields—chemistry and physics Chemistry isthe study of matter and the interactions of matter Physics isthe study of energy and its ability to change matter Figure 6shows physical scientists at work
This chemist is studying the light emitted by certain compounds.
This physicist is studying light as
it travels through optical fibers.
Figure 6 Physical scientists
study a wide range of subjects.
Trang 38SECTION 1 What is science? 11
• Scientists ask questions to learn how, why, or when something occurred.
• A theory is a possible explanation for tions that is supported by many investigations.
observa-• A scientific law describes a pattern but does not explain why things happen
Systems in Science
• A system is composed of structures, cycles, and processes that interact with each other.
The Branches of Science
• Science is divided into three branches—life science, Earth science, and physical science.
• Technology is the application of science in our everyday lives.
5 Infer Scientists ask questions and make observations What types of questions and observations would you make if you were a scientist studying schools of fish in the ocean.
Careers Chemists ask questions such as “Howcan I make plastic stronger?” or “What can I do tomake aspirin more effective?” Physicists mightask other types of questions, such as “How doeslight travel through glass fibers?” or “How canhumans harness the energy of sunlight for theirenergy needs?”
Many careers are based on the physical ences Physicists and chemists are some obviouscareers Ultrasound and X-ray technicians work-ing in the medical field study physical science becausethey study the energy in ultrasound or X rays and how itaffects a living system
sci-Science and Technology Although learning theanswers to scientific questions is important, theseanswers do not help people directly unless they can be
applied in some way Technology is the practical use of
apply science to develop technology The study of how to use theenergy of sunlight is science Using this knowledge to createsolar panels is technology The study of the behavior of light as
it travels through thin, glass, fiber-optic wires is science The use
of optical fibers to transmit information is technology A tist uses science to study how the skin of a shark repels water
scien-The application of this knowledge to create a material that helpsswimmers slip through the water faster is technology
Figure 7 Solar-powered cars and the swimsuits worn in the Olympics are examples of technol- ogy—the application of science.
red.msscience.com/self_check_quiz
Trang 39Science Skills
You know that science involves asking questions, but howdoes asking questions lead to learning? Because no single way togain knowledge exists, a scientist doesn’t start with step one,then go to step two, and so on Instead, scientists have a hugecollection of skills from which to choose Some of these skillsinclude thinking, observing, predicting, investigating, research-ing, modeling, measuring, analyzing, and inferring Science alsocan advance with luck and creativity
Science Methods Investigations often follow a general
see-ing somethsee-ing and then asksee-ing a question about what wasobserved Scientists often perform research by talking with otherscientists They read books and scientific magazines to learn asmuch as they can about what is already known about their ques-tion Usually, scientists state a possible explanation for theirobservation To collect more information, scientists almostalways make more observations They might build a model ofwhat they study or they might perform investigations Often,they do both How might you combine some of these skills in aninvestigation?
■ Identifysome skills scientists use.
■ Definehypothesis.
■ Recognizethe difference between
observation and inference.
Science can be used to learn more
about the world you live in.
Review Vocabulary
observation: a record or
descrip-tion of an occurrence or pattern in
Repeat several times
Hypothesis not supported
Modify hypothesis
Figure 8 Although there are
differ-ent scidiffer-entific methods for investigating
a specific problem, most investigations
follow a general pattern.
Trang 40SECTION 2 Science in Action 13
Questioning and Observing Ms Clark placed a sealed shoebox on the table at the front of the laboratory Everyone in theclass noticed the box Within seconds the questions flew
“What’s in the box?” “Why is it there?”
Ms Clark said she would like the class to see how they usedsome science skills without even realizing it
“I think that she wants us to find out what’s in it,” Isabellesaid to Marcus
“Can we touch it?” asked Marcus
“It’s up to you,” Ms Clark said
Marcus picked up the box and turned it over a few times
“It’s not heavy,” Marcus observed “Whatever is inside slidesaround.” He handed the box to Isabelle
Isabelle shook the box The class heard the object strike thesides of the box With every few shakes, the class heard a metal-lic sound The box was passed around for each student to makeobservations and write them in his or her Science Journal Some
Taking a Guess “I think it’s a pair of scissors,” said Marcus
“Aren’t scissors lighter than this?” asked Isabelle, while ing the box “I think it’s a stapler.”
shak-“What makes you think so?” asked Ms Clark
“Well, staplers are small enough to fit inside a shoe box, and
it seems to weigh about the same,” said Isabelle
“We can hear metal when we shake it,” said Enrique
“So, you are guessing that a stapler is in the box?”
“Yes,” they agreed
“You just stated a hypothesis,” exclaimed Ms Clark
“A what?” asked Marcus
Figure 9 Investigations often begin by making observations and asking questions.
It's not very heavy.
What's that metal-like sound? It sounds like
a stapler.
Biologist Some ists study the livingworld, using mostly theirobservational skills Theyobserve animals andplants in their naturalenvironment, taking carenot to disturb the organ-isms they are studying.Make observations oforganisms in a nearbypark or backyard Recordyour observations in yourScience Journal