Program Authors Dr. Dorothy J. T. Terman Dr. Jay K. Hackett Science Curriculum Development Consultant Former K–12 Science and Mathematics Coordinator Irvine Unified School District, CA Irvine, CA Professor Emeritus of Earth Sciences University of Northern Colorado Greeley, CO Dr. Richard H. Moyer Professor of Science Education and Natural Sciences University of Michigan–Dearborn Dearborn, MI Dr. JoAnne Vasquez Elementary Science Education Consultant NSTA Past President Member, National Science Board and NASA Education Board Dr. Gerald F. Wheeler Executive Director National Science Teachers Association Bank Street College of Education New York, NY Contributing Authors Dr. Sally Ride Sally Ride Science San Diego, CA Mulugheta Teferi, M.A. Lucille Villegas Barrera, M.Ed. Principal, Gateway Middle School Center of Math, Science, and Technology St. Louis Public Schools St. Louis, MO Elementary Science Supervisor Houston Independent School District Houston, TX Dinah Zike, M.Ed. Dinah Might Adventures LP San Antonio, TX Kathryn LeRoy, M.S. Executive Director Division of Mathematics and Science Education Miami-Dade County Public Schools, FL Miami, FL American Museum of Natural History New York, NY Contributing Writer Ellen C. Grace, M.S. Consultant Albuquerque, NM Students with print disabilities may be eligible to obtain an accessible, audio version of the pupil edition of this textbook. Please call Recording for the Blind & Dyslexic at 1-800-221-4792 for complete information. A Copyright © 2008 by The McGraw-Hill Companies, Inc. All rights reserved. Except as permitted under the United States Copyright Act, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without prior permission of the publisher. Send all inquiries to: Glencoe/McGraw-Hill 8787 Orion Place Columbus, OH 43240-4027 ISBN: MHID: 978-0-02-287197-0 0-02-287197-7 Printed in the United States of America. 1