All photographs belong to Holt, Rinehart and Winston, Inc., by Sam Dudgeon except:

Bill Hubbell/HRW
Corbis Images
Digital Imagery® copyright PhotoDisc, Inc.
Digital Vision Ltd.
Eyewire Inc.
European Communities©
Elephant Productions/HRW
John Foxx images
John Langford/HRW
Library of Congress
Marty Granger/HRW
Michael Paras/International Stock
Michael Young/HRW
Penni Gladstone/Outline Press
Photodisc, Inc.
Sergio Purtell/HRW
Top Drawer Productions/HRW
EclectiCollections: Mary, Queen of Scots image
Photographs of Robert Frost, Martin Luther King, Jr., courtesy Library of Congress
Photographs of Anne Frank, Edgar Allan Poe, E. E. Cummings, and Shakespeare, courtesy New York Public Library

Environmental Science
Bird, tree frog, walrus, sunflower, crowd, tiger, desert sky, atmosphere, Hong Kong, penguins, forest, river, pelican, Washington DC photographs courtesy Digital Stock Corp. Fish, Peru, cupped hand, earth, people in field, market, terrace farming, power, windmill, waste barrel, leaves, desert photographs ©1998 Photodisc, Inc. Maps courtesy Mountain High Maps® ©1995

GeoTreks Activities
CORBIS/Brian Vikander
CORBIS/Tim Thompson Robert Fried/Stock, Boston/Picture Quest
CORBIS/Galen Rowell
CORBIS/Dave G. Houser
Angelo Cavalli/eStock Photography/Picture Quest
Bob Krist/eStock Photography/Picture Quest
CORBIS/Keren Su CORBIS/Nik Wheeler
CORBIS/Stephanie Maze
Carlos Humberto T.D.C./Contact Press Images/Picture Quest
CORBIS/Penny Tweedie
Ann Purcell; Carl Purcell/Words and Pictures/Picture Quest
CORBIS/David Lees
CORBIS/© HorreeZirkzee Produkties
CORBIS/Richard T. Nowitz
David Young-Wolff/Photo Edit/Picture Quest
CORBIS/Eric Crichton

Kit Houghton/CORBIS
©Corbis Images/PictureQuest
CORBIS/Michael S. Yamashita
CORBIS/Tom Bean
CORBIS/Vince Streano
Yoav Levy/Phototake/Picture Quest
CORBIS/Peter Turnley Courtesy of Texas Highways Magazine
CORBIS/Marc Muench
CORBISJames Marshall
CORBIS David Muench
CORBIS/Anna Clopet
Andre Jenny/Focus Group/Picture Quest
CORBIS/Annie Griffiths Belt
Image Copyright ©2001 PhotoDisc, Inc./NASA/HRW
©C. Lee/PhotoLink/PhotoDisc/PictureQuest/HRW
©Corbis Images/Picture Quest/HRW
CORBIS/Staffan Widstrand
© Stockbyte
Mark Downey/Lucid Images/Picture Quest
CORBIS/Pablo Corral V CORBIS/Yann Arthus-Bertrand
CORBIS/Wolfgang Kaehler
CORBIS/Jack Fields
©Mireille Vautier/Woodfin Camp/Picture Quest
©Michelle Burgess/Index Stock Imagery/Picture Quest
CORBIS/Tony Arruza ©Rick Bostick/Southern Stock/PictureQuest
©David Perdew/Focus Group/PictureQuest
CORBIS/Dean Conger
CORBIS/Pat O’Hara Sovfoto/Eastfoto/Picture Quest
CORBIS/Caroline Penn CORBIS/Ric Ergenbright
CORBIS/Alison Wright
©Keren Su/Stock, Boston/PictureQuest
CORBIS/Werner Forman Ann Purcell; Carl Purcell/Words and Pictures/Picture Quest
CORBIS/Tim Page
Corbis Images/Picture Quest
H. Wiesenhofer/PhotoLink/PhotoDisc/Picture Quest

PhotoSphere Images/Picture Quest
CORBIS/David Rubinger
CORBIS/Roger Wood
CORBIS/Dave Bartruff
CORBIS/Robert Holmes
CORBIS/Gian Berto Vanni
CORBIS/Bojan Breceli
CORBIS/Eric & David Hosking
CORBIS/Robert van der Hilst ©PhotoSpin, Inc.
CORBIS/Paul Almasy
CORBIS/Roger Tidman
CORBIS/Anthony Bannister
CORBIS/Carl Purcell
Image © PhotoDisc, Inc./HRW
CORBIS/AFP CORBIS/Owen Franken Ann Purcell; Carl Purcell/Words & Pictures/PictureQuest ©PhotoSphere Images/PictureQuest/HRW
Jeremy Hoare/Life File/PhotoDisc/Picture Quest
CORBIS/Lindsay Hebberd
CORBIS/Shelley Gazin
CORBIS/Wayne Lawler
©Digital Vision/PictureQuest
©Joshua Ets-Hokin/PhotoDisc/PictureQuest
CORBIS/Charles Lenars
CORBIS/David S. Robbins
©Glen Allison/PhotoDisc/PictureQuest
CORBIS/David Cumming/Eye Ubiquitous
©PhotoSphere Images/PictureQuest
CORBIS/David Samuel Robbins Matthew Phillips/Photo Network/Picture Quest
CORBIS/Geoff Moon;Frank Lane Picture Agency
CORBIS/Paul A. Souders

Social Studies
NARA Images: Courtesy of National Archives
Corbis Images
Digital Imagery, The PhotoDisc, Inc.
Digital Vision
Property of HRW/Library of Congress
30.10.H.259 United We Win-NARA Images: Courtesy of National Archives
30.70.C.011 Constitution-NARA Images: Courtesy of National Archives
615.00.D.003 Douglass, Frederic-NARA Images: Courtesy of National Archives
SPC0001A.JPG shuttle endeavor-Corbis Images
SS28013.JPG Grand Teton-Digital Imagery, The PhotoDisc, Inc.
013 CW military railroad-Corbis Images
505.00.040 Map-Digital Imagery, The PhotoDisc, Inc.
168128A.JPG multicultural teens-Digital Vision
TRN0024B.JPG transportation-Corbis Images
OS43088.JPG sextant-Digital Imagery, The PhotoDisc, Inc.
FA03047.TIF the Americas-HRW Photo by Sam Dudgeon
7.580 Farm workers children-Property of HRW/Library of Congress