1、PhotoDisci-01-LBN-861773 8/24/04 9:55 AM Page iElectricity andMagnetismIron filings cluster around thenorth and south poles of a barmagnet because of magneticforce.Magnetic force is exertedthrough a magnetic field,which is outlined by the ironfilings.This field is caused bynegatively charged electro
2、nsspinning in the atoms.Send all inquiries to:Glencoe/McGraw-Hill8787 Orion PlaceColumbus,OH 43240-4027ISBN:0-07-861773-1Printed in the United States of America.2 3 4 5 6 7 8 9 10 027/111 09 08 07 06 05 04Copyright 2005 by The McGraw-Hill Companies,Inc.All rights reserved.Except as permitted underth
3、e United States Copyright Act,no part of this publication may be reproduced or distributed in anyform or by any means,or stored in a database or retrieval system,without prior written permission of the publisher.The National Geographic features were designed and developed by the National Geographic
4、SocietysEducation 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 writtenpermission,is strictly prohibited.The“Science and Society”and the“Science and History”features that a
5、ppear in this book weredesigned and developed by TIME School Publishing,a division of TIME Magazine.TIME and the redborder are trademarks of Time Inc.All rights reserved.PhotoDisci-01-LBN-861773 8/24/04 9:55 AM Page iiCONTENT Jack CooperEnnis High SchoolEnnis,TXCarl Zorn,PhDStaff ScientistJefferson
6、Laboratory Newport News,VAMATH Michael Hopper,DEngManager of Aircraft Certification L-3 CommunicationsGreenville,TXREADING Barry BartoSpecial Education TeacherJohn F.Kennedy ElementaryManistee,MIRachel Swaters-KissingerScience Teacher John Boise Middle SchoolWarsaw,MOSAFETY Sandra West,PhDDepartment
7、 of BiologyTexas State University-San MarcosSan Marcos,TXACTIVITY TESTERS Nerma Coats HendersonPickerington Lakeview Jr.HighSchoolPickerington,OHMary Helen Mariscal-CholkaWilliam D.Slider Middle SchoolEl Paso,TXScience Kit and BorealLaboratoriesTonawanda,NYNiiiAuthorsSeries ConsultantsDeidre AdamsWe
8、st Vigo Middle SchoolWest Terre Haute,IN Karen CurryEast Wake Middle School Raleigh,NC Anthony J.DiSipio,Jr.8th Grade ScienceOctorana Middle SchoolAtglen,PAGeorge GabbGreat Bridge Middle SchoolChesapeake Public SchoolsChesapeake,VASeries ReviewersEducation DivisionWashington,D.C.Cathy EzrailsonScien
9、ce Department HeadAcademy for Science and Health ProfessionsConroe,TXMargaret K.ZornScience WriterYorktown,VADinah ZikeEducational ConsultantDinah-Might Activities,Inc.San Antonio,TXi-01-LBN-861773 8/24/04 9:55 AM Page iiiWhy do I need my science book?Have you ever been in class andnot understood al
10、l of what waspresented?Or,you understoodeverything in class,but at home,got stuck on how to answer aquestion?Maybe you just wondered when you were evergoing 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!B
11、efore You ReadChapter OpenerScience is occurring all around you,and the opening photo of each chapter will preview thescience you will be learning about.The ChapterPreview will give you an idea of what you will belearning about,and you can try the Launch Lab tohelp get your brain headed in the right
12、 direction.TheFoldables exercise is a fun way to keep you organized.Section OpenerChapters are divided into two to foursections.The As You Read in the margin of the firstpage of each section will let you know what is mostimportant in the section.It is divided into four parts.What Youll Learn will te
13、ll you the major topics youwill be covering.Why Its Important will remind youwhy you are studying this in the first place!TheReview 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 youneed to learn to underst
14、and this section.These wordswill be in boldfaced print and highlighted in thesection.Make a note to yourself to recognize thesewords as you are reading the section.(bkgd)John Evans,(inset)PhotoDisci-01-LBN-861773 8/24/04 9:55 AM Page ivAs You ReadHeadingsEach section has a titlein large red letters,
15、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.MarginsIn the margins ofyour text,you will find many helpfulresources.The Science Online exercises andIntegrate activities help you explore
16、 the topicsyou are studying.MiniLabs reinforce the sci-ence concepts you have learned.Building SkillsYou also will find anApplying Math or Applying Science activityin each chapter.This gives you extra prac-tice using your new knowledge,and helpsprepare you for standardized tests.Student ResourcesAt the end of the bookyou will find Student Resources to help youthroughout your studies.These includeScience,Technology,and Math Skill Hand-books,an English/Spanish Glossary,and anIndex.Also,use your Fo