1:100,000 topo. map, © U.S. Geological Survey
(Grade 5/Unit 1)
1:24,000 topo. map, © U.S. Geological Survey
(Grade 5/Unit 1)
1:50,000 topo. map, © U.S. Geological Survey
(Grade 5/Unit 1)
Acorn barnacle, © L.L. Rue IV/Bruce Coleman Inc.
(Grade 4/Unit 2)
Adult mayfly, © Robert C. Simpson/Visuals Unlimited
(Grade 3/Unit 3)
Aerial of deranged drainage, © Yann Arthus-Bertrand/Corbis
(Grade 5/Unit 1)
Aerial of river system, © Getty Images, Inc.
(Grade 5/Unit 1)
Aerial, estuary #1, © Joy Spurr/Bruce Coleman Inc.
(Grade 5/Unit 2)
Aerial, estuary #2, © Getty Images, Inc.
(Grade 5/Unit 2)
Aerial, estuary #3, © Yann Arthus-Bertrand/Corbis
(Grade 5/Unit 2)
Anemometer, © Terry Gleason/Visuals Unlimited
(Grade 3/Unit 1)
Anemones, © Phil Degginger/Bruce Coleman Inc.
(Grade 5/Unit 2)
Angler fish, © IQ3d-visual & written/Bruce Coleman Inc.
(Grade 5/Unit 2)
Ann Morgan #2, © Courtesy of Mount Holyoke College Archives and Special Collections
Grade 3/Unit 3)
Antarctic cod, © Galen Rowell/Corbis
(Grade 4/Unit 1)
Arctic fox, © Ken Graham/Bruce Coleman Inc.
(Grade 3/Unit 4)
Atoll with lagoon, © Douglas Peebles/Corbis
(Grade 3/Unit 3)
Baby birds respond to parent, © Fotopic International/West Stock, Inc.
(Grade 4/Unit 2)
Baby lynx in rotting stump, © Tom Brakefield/Bruce Coleman Inc.
(Grade 4/Unit 1)
Bacteria, © SIMKO/Visuals Unlimited
(Grade 4/Unit 1)
Bacteria (re-use), © SIMKO/Visuals Unlimited
(Grade 4/Unit 1)
Bamboo for pulp, © Wolfgang Kaehler/Corbis
(Grade 4/Unit 1)
Barometer project, © K12 Inc.
(Grade 3/Unit 1)
Bat, © Getty Images, Inc.
(Grade 3/Unit 2)
Beads of mercury, © Getty Images, Inc.
(Grade 3/Unit 5)
Beaufort Spinner, © K12 Inc.
(Grade 3/Unit 1)
Beautiful water shot, © Getty Images, Inc.
(Grade 5/Unit 2)
Bee pollinating apple blossom, © Getty Images, Inc.
(Grade 4/Unit 1)
Bee pollinating flower, © Getty Images, Inc.
(Grade 4/Unit 2)
Bird on a sandy beach, © Windland Rice/Bruce Coleman Inc.
(Grade 5/Unit 2)
Bison grazing, © Raymond Gehman/Corbis
(Grade 4/Unit 2)
Blackberry bush, © Bruce Coleman Inc.
(Grade 4/Unit 2)
Black-footed ferret, © D. Robert & Lorri Franz/Corbis
(Grade 4/Unit 2)
Bog with moss, © Getty Images, Inc.
(Grade 5/Unit 1)
Boiling kettle, © David Wrobel/Visuals Unlimited
(Grade 3/Unit 5)
Boreal forest (taiga), © O. Kosterin/Bruce Coleman Inc.
(Grade 3/Unit 3)
Boreal forest (taiga), © O. Kosterin/Bruce Coleman Inc.
(Grade 3/Unit 3)
Boy on rock by water, © Corbis
(Grade 4/Unit 1)
Brown trout (magnifier tool), © Ken Lucas-Photo/Visuals Unlimited
(Grade 3/Unit 2)
Cactus in desert, © Gunter Marx/Corbis
(Grade 3/Unit 3)
Cactus in desert, © Getty Images, Inc.
(Grade 4/Unit 1)
Cactus plant, © Getty Images, Inc.
(Grade 4/Unit 1)
California condor, © Kenneth W. Fink/Bruce Coleman Inc.
(Grade 4/Unit 2)
Camouflaged octopus, © Getty Images, Inc.
(Grade 4/Unit 2)
Child blowing up balloon, © Cheryl A. Ertelt/Visuals Unlimited
(Grade 3/Unit 1)
Child brushing teeth, © Richard Hutchings/Corbis
(Grade 5/Unit 2)
Child on pond bank, © Getty Images, Inc.
(Grade 3/Unit 3)
Child planting tree, © Gary Braasch/Corbis
(Grade 5/Unit 1)
Cirrus clouds, © Getty Images, Inc.
(Grade 3/Unit 1)
Clay soil, © D. Yeske/Visuals Unlimited
(Grade 5/Unit 1)
Clean stream in city, © Steve Raymer/Corbis
(Grade 5/Unit 1)
Close-up of acacia tree, © Michael & Patricia Fogden/Corbis
(Grade 4/Unit 2)
Clouds over lake, © Getty Images, Inc.
(Grade 3/Unit 1)
Coal seam, © Nicholas De Vore/Bruce Coleman Inc.
(Grade 3/Unit 4)
Coal/rocks, © Getty Images, Inc.
(Grade 4/Unit 1)
Colored liquids pouring, © Larry Stepanowicz/Visuals Unlimited
(Grade 3/Unit 5)
Colorful coral reef, © Getty Images, Inc.
(Grade 3/Unit 3)
Community stream cleanup, © Getty Images, Inc.
(Grade 5/Unit 1)
Cool, sunny day, © Getty Images, Inc.
(Grade 3/Unit 1)
Coral colony, © Ronald Sefton/Bruce Coleman Inc.
(Grade 3/Unit 3)
Coral polyp, open, © Colla-V&W/Bruce Coleman Inc.
(Grade 3/Unit 3)
Coral reef structure-reuse, © Getty Images, Inc.
(Grade 3/Unit 4)
Cornell-Gilbert mastadon jaw, © Courtesy Cornell
News Service
(Grade 3/Unit 4)
Crabs on a seashore, © Norman Owen Tomalin/Bruce
Coleman Inc.
(Grade 3/Unit 4)
Cricket, © Getty Images, Inc.
(Grade 3/Unit 5)
Crop-dusting, © Robert P. Carr/Bruce Coleman Inc.
(Grade 5/Unit 1)
Cumulonimbus cloud, © M. Dillon/Corbis
(Grade 3/Unit 1)
Cumulus clouds, © Getty Images, Inc.
(Grade 3/Unit 1)
Dandelions, © Gary W. Carter/Visuals Unlimited
(Grade 4/Unit 1,4)
Darwin's finch, C. Parvulus, © John Guistana/Bruce
Coleman Inc.
(Grade 4/Unit 2)
Darwin's finch, G. magnarostris, © Tui DeRoy/Bruce
Coleman Inc.
(Grade 4/Unit 2)
Deciduous tree, © Getty Images, Inc.
(Grade 4/Unit 4)
Decomposition station, © K12 Inc.
(Grade 4/Unit 1)
Deep zone sea star, © Richard Herrmann/Visuals
Unlimited
(Grade 5/Unit 2)
Deer, © Brenda Davison/Corbis
(Grade 4/Unit 1)
Deer eating dandelions, © Gustav W. Verderber/Visuals
Unlimited
(Grade 4/Unit 1)
Deer eating leaves, © Brenda Davison/Corbis
(Grade 4/Unit 1)
Desert, © Getty Images, Inc.
(Grade 3/Unit 3)
Dew on spider web, © Getty Images, Inc.
(Grade 3/Unit 1)
Dino skeleton and scientists, © Reuters New Media
Inc./Corbis
(Grade 3/Unit 4)
Doorway, © Jeff Greenberg/Visuals Unlimited
(Grade 3/Unit 5)
Doppler radar, © Gene Rhoden/Visuals Unlimited
(Grade3/Unit 1)
Duck with ducklings, © Getty Images, Inc.
(Grade 4/Unit 2)
Duckling, © Lindsey P. Martin/Corbis
(Grade 4/Unit 1)
Dungeness crab, © Ted Streshinsky/Corbis
(Grade 4/Unit 2)
Earth with water colored, © NASA
(Grade 5/Unit 1)
Earthworm/soil, © Getty Images, Inc.
(Grade 4/Unit 1)
Earthworms, © Getty Images, Inc.
(Grade 4/Unit 1)
Echidna, © Erwin & Peggy Bauer/Bruce Coleman
Inc.
(Grade 3/Unit 2)
Electromagnet, © Leslie Garland Picture Library/Alamy
(Grade 4/Unit 7)
Elephant profile, © Bruce Aiken/Bruce Coleman
Inc.
(Grade 3/Unit 4)
Evaporated lemonade, © K12 Inc.
(Grade 4/Unit 3)
Evenly mixed pile of laundry, © K12 Inc.
(Grade 4/Unit 3)
Everglades with alligators, © Getty Images, Inc.
(Grade 5/Unit 1)
Expansive view of ocean, © Robert Holmes/Corbis
(Grade 3/Unit 3)
Exposed dinosaur fossils, © James L. Amos/Corbis
(Grade 3/Unit 4)
Family picnic, © Getty Images, Inc.
(Grade 4/Unit 1)
Feather, © Jerome Wexler/Visuals Unlimited
(Grade 3/Unit 5)
Field and factory, © Getty Images, Inc.
(Grade 5/Unit 1)
Fiji crested iguana, © John Giustina/Bruce Coleman
Inc.
(Grade 3/Unit 2)
Fiji crested iguana, © John Giustina/Bruce Coleman
Inc.
(Grade 3/Unit 2)
Filtering sand from water, © K12 Inc.
(Grade 4/Unit 3)
Fishing trawler, © Jeffrey L. Rotman/Corbis
(Grade 4/Unit 2)
Flowers in clumped distribution, © Getty Images,
Inc.
(Grade 4/Unit 2)
Fossil fish school, © James L. Amos/Corbis
(Grade 3/Unit 4)
Fossil shrimp, © Kevin Schafer/Corbis
(Grade 3/Unit 4)
Fossil starfish, © Kevin Schafer/Corbis
(Grade 3/Unit 4)
Fox chasing rabbit in snow, © Tom Brakefield/Corbis
(Grade 4/Unit 1)
Fragile reef, © Lawson Wood/Corbis
(Grade 3/Unit 3)
Fringe reef, © Paul A. Souders/Corbis
(Grade 3/Unit 3)
Frog, © Getty Images, Inc.
(Grade 3/Unit 2;Grade 4/Unit 1)
Frog eggs, © G.L. Twiest/Visuals Unlimited
(Grade 3/Unit 2)
Gannet colony, © Getty Images, Inc.
(Grade 4/Unit 2)
Garden with veggies and weeds, © Lynda Richardson/Corbis
(Grade 4/Unit 2)
Gases rising from volcano, © Marty Snyderman/Visuals
Unlimited
(Grade 3/Unit 5)
Geese on a pond, © Iain Davidson/Alamy Images
(Grade 3/Unit 3)
Giraffe eating leaves, © Getty Images, Inc.
(Grade 4/Unit 1)
Glacial landscape, © John Corbett/Corbis
(Grade 3/Unit 4)
Glacier-sculpted valley, © David Muench/Corbis
(Grade 3/Unit 4)
Glass of soda, © Corbis
(Grade 4/Unit 3)
Golden Gate Bridge, © Hal Beral/Visuals Unlimited
(Grade 3/Unit 5)
Graduated cylinders with liquid, © Larry Stepanowicz/Visuals
Unlimited
(Grade 3/Unit 5)
Grass, closeup, © Getty Images, Inc.
(Grade 4/Unit 1)
Grasshopper, © Getty Images, Inc.
(Grade 4/Unit 1)
Grasslands, © John Shaw/Bruce Coleman Inc.
(Grade 3/Unit 3)
Grasslands, © Michele Burgess/Corbis
(Grade 3/Unit 3)
Great Barrier Reef, © Robert Holmes/Corbis
(Grade 3/Unit 3)
Great white shark, © Ron & Val Taylor/Bruce
Coleman Inc.
(Grade 3/Unit 2)
Gypsum rock, © Ken Lucas/Visuals Unlimited
(Grade 3/Unit 4)
Hawk eating snake, © Joe McDonald/Corbis
(Grade 4/Unit 1)
Hermit crab, © ViRGili-V&W/Bruce Coleman Inc.
(Grade 5/Unit 2)
Hikers referring to topo. map, © Getty Images,
Inc.
(Grade 5/Unit 1)
Hostas, © Eric Crichton/Corbis
(Grade 4/Unit 1)
Housefly, © Clive Druett; Papilio/Corbis
(Grade 4/Unit 1)
Hunting dog on point, © Dale C. Spartas/Corbis
(Grade 4/Unit 2)
Hygroclimograph, © John D. Cunningham/Visuals
Unlimited
(Grade 3/Unit 1)
Hygrometer project, © K12 Inc.
(Grade 3/Unit 1)
Ice core drilling, © Morton Beebe/Corbis
(Grade 3/Unit 4)
Ice core with scale, © Roger Ressmeyer/Corbis
(Grade 3/Unit 4)
Igneous/Meta rock (basalt), © Albert J. Copley/Visuals
Unlimited
(Grade 5/Unit 1)
Insect eating leaf, © Peter Johnson/Corbis
(Grade 4/Unit 2)
Insects eating dead leaves, © Eric & David
Hosking/Corbis
(Grade 4/Unit 1)
Inside bee hive with queen, © Carlos Sanz-V&W/Bruce
Coleman Inc.
(Grade 4/Unit 2)
Irrigation, © David Frazier/Corbis
(Grade 5/Unit 2)
Japanese cranes courting, © Steve Kaufman/Corbis
(Grade 4/Unit 2)
Jellyfish in ocean, © NOAA
(Grade 4/Unit 1)
Kangaroo, © Al Franklin/Corbis
(Grade 3/Unit 2)
Killer whale, © Amos Nachoum/Corbis
(Grade 4/Unit 2)
Kingfisher eating fish, © Jeremy Woodhouse/Corbis
(Grade 4/Unit 1)
Kirtland warbler, © Ron Austing; Frank Lane Picture
Agency/Corbis
(Grade 4/Unit 2)
Lake landscape, © Getty Images, Inc.
(Grade 3/Unit 3)
Lake with minimal surroundings, © Getty Images,
Inc.
(Grade 5/Unit 1)
Lamprey, © Hans Reinhard/Bruce Coleman Inc.
(Grade 3/Unit 2)
Large herd of reindeer, © Getty Images, Inc.
(Grade 4/Unit 2)
Large spectacular wetland, © Getty Images, Inc.
(Grade 5/Unit 1)
Leaves, © Getty Images, Inc.
(Grade 4/Unit 1)
Leech, © Anthony Bannister/Corbis
(Grade 4/Unit 2)
Lesson Opener: barnacle, © George D. Lepp/Corbis
(Grade 4/Unit 2)
Lesson Opener: bison, © Raymond Gehman/Corbis
(Grade 4/Unit 2)
Lesson Opener: city stream, © Steve Raymer/Corbis
(Grade 5/Unit 1)
Lesson Opener: coral reef, © Getty Images, Inc.
(Grade 3/Unit 3)
Lesson Opener: crashing wave, © Getty Images,
Inc.
(Grade 5/Unit 2)
Lesson Opener: cylinders, © Larry Stepanowicz/Visuals
Unlimited
(Grade 3/Unit 5)
Lesson Opener: deciduous tree, © Getty Images,
Inc.
(Grade 4/Unit 1)
Lesson Opener: estuary, © Yann Arthus-Bertrand/Corbis
(Grade 5/Unit 2)
Lesson Opener: forest, © Mark Taylor/Bruce Coleman
Inc.
(Grade 3/Unit 4)
Lesson Opener: gannets, © Getty Images, Inc.
(Grade 4/Unit 2)
Lesson Opener: high tide, © Tim Hauf Photography/Visuals
Unlimited
(Grade 5/Unit 2)
Lesson Opener: hikers with map, © Getty Images,
Inc.
(Grade 5/Unit 1)
Lesson Opener: hot spring, © Joe McDonald/Visuals
Unlimited
(Grade 3/Unit 5)
Lesson Opener: leech, © Anthony Bannister/Corbis
(Grade 4/Unit 2)
Lesson Opener: melting ice, © Getty Images, Inc.
(Grade 3/Unit 5)
Lesson Opener: mountain goats, © W. Wayne Lockwood,
M.D./Corbis
(Grade 4/Unit 2)
Lesson Opener: musk oxen, © Brian A. Vikander/Corbis
(Grade 3/Unit 4)
Lesson Opener: panda, © Warren Jacobi/Corbis
(Grade 4/Unit 1)
Lesson Opener: river system, © Getty Images, Inc.
(Grade 5/Unit 1)
Lesson Opener: rusty nail, © Getty Images, Inc
(Grade 4/Unit 3)
Lesson Opener: sea ice, © Getty Images, Inc.
(Grade 5/Unit 2)
Lesson Opener: sea otter, © Jeff Foott/Bruce Coleman
Inc.
(Grade 4/Unit 2)
Lesson Opener: sea urchins, © Ron Sefton/Bruce
Coleman Inc.
(Grade 5/Unit 2)
Lesson Opener: steep hillside, © Yann Arthus-Bertrand/Corbis
(Grade 5/Unit 1)
Lesson Opener: tick, © Joe McDonald/Corbis
(Grade 4/Unit 2)
Lesson Opener: tree rings, © Doug Wilson/Corbis
(Grade 4/Unit 4)
Lesson Opener: trilobytes, © Kevin Schafer/Corbis
(Grade 3/Unit 4)
Lesson Opener: wetland, © Getty Images, Inc.
(Grade 5/Unit 1)
Limestone fossils, © Joe McDonald/Bruce Coleman
Inc.
(Grade 3/Unit 4)
Lion with cub, © Joe McDonald/Bruce Coleman Inc.
(Grade 3/Unit 2)
Liter bottle, © K12 Inc.
(Grade 3/Unit 5)
Lush coniferous forest, © Mark Taylor/Bruce Coleman
Inc.
(Grade 3/Unit 4)
Mammal running (cheetah), © Corbis
(Grade 3/Unit 2)
Mammoth hunt illustration, © Gianni Dagli Orti/Corbis
(Grade 3/Unit 4)
Mammoth illustration, © Jonathan Blair/Corbis
(Grade 3/Unit 4)
Mangrove seed germinating, © William Webber/Visuals
Unlimited
(Grade 5/Unit 2)
Mangrove tree, © Ivan Polunin/Bruce Coleman Inc.
(Grade 5/Unit 2)
Marine ecosystem (coral reef), © Getty Images,
Inc.
(Grade 3/Unit 3)
Marlin, © Tony Arruza/Bruce Coleman Inc.
(Grade 5/Unit 2)
Marsh with reeds, sawgrass, © Wendell Metzen/Bruce
Coleman Inc.
(Grade 5/Unit 1)
Mayfly nymph, © Science Pictures Limited/Corbis
(Grade 3/Unit 3)
Melting ice and water drops, © Getty Images, Inc.
(Grade 3/Unit 5)
Melting ice cream, © Getty Images, Inc.
(Grade 3/Unit 5)
Metered man, © Bettmann/Corbis
(Grade 3/Unit 5)
Microscopic bacteria, © SIMKO/Visuals Unlimited
(Grade 4/Unit 1)
Mistletoe on a tree, © Frank Blackburn/Corbis
(Grade 4/Unit 2)
Mold on lemon, © Danilo Donadoni/Bruce Coleman
Inc.
(Grade 4/Unit 1)
Mom with children, © Getty Images, Inc.
(Grade 3/Unit 2)
Mother predator teaching cubs, © Joe McDonald/Corbis
(Grade 4/Unit 2)
Mountain goats fighting, © W. Wayne Lockwood,
M.D./Corbis
(Grade 4/Unit 2)
Mouse, © E.R. Degginger/Bruce Coleman Inc.
(Grade 4/Unit 1)
Mushrooms on stump, © Link/Visuals Unlimited
(Grade 4/Unit 1)
Musk oxen herd on tundra, © Brian A. Vikander/Corbis
(Grade 3/Unit 4)
Musk oxen in defense circle, © Erwin & Peggy
Bauer/Bruce Coleman Inc.
(Grade 4/Unit 2)
Nile region from Space, © Getty Images, Inc.
(Grade 5/Unit 1)
Nile River scene, © Mark Karrass/Corbis
(Grade 5/Unit 1)
Nixon, © Hulton-Archive/Getty Images, Inc.
(Grade 5/Unit 1)
Ocean at high tide, © Tim Hauf Photography/Visuals
Unlimited
(Grade 5/Unit 2)
Ocean at low tide, © Tim Hauf Photography/Visuals
Unlimited
(Grade 4/Unit 2)
Orange tree, © PictureNet/Corbis
(Grade 4/Unit 1)
Panda eating bamboo, © Warren Jacobi/Corbis
(Grade 4/Unit 1)
Penguins, © Image Life/Corbis
(Grade 3/Unit 2)
People walking in the rain, © Steve Estvanik/Corbis
(Grade 3/Unit 1)
Periwinkle, © John D. Cunningham/Visuals Unlimited
(Grade 5/Unit 2)
Petrified forest in winter, © David Muench/Corbis
(Grade 3/Unit 4)
Pile of laundry, © K12 Inc.
(Grade 4/Unit 3)
Poison ivy, © Getty Images, Inc.
(Grade 4/Unit 2)
Polar bear, © Tom Brakefield/Bruce Coleman Inc.
(Grade 3/Units 2,3)
Political map, © John Henry Williams/Bruce Coleman
Inc.
(Grade 5/Unit 1)
Pond, © Getty Images, Inc.
(Grade 3/Unit 2)
Pond, © Getty Images, Inc.
(Grade 3/Unit 3)
Pond, © Getty Images, Inc.
(Grade 5/Unit 1)
Pond with ducks, © Steve Alden/West Stock, Inc.
(Grade 5/Unit 1)
Pond, wide shot, © John Shaw/Bruce Coleman Inc.
(Grade 3/Unit 3)
Porcelain vase, © Getty Images, Inc.
(Grade 3/Unit 5)
Prairie dog, © Getty Images, Inc.
(Grade 3/Unit 3)
Prairie dog on alert, © Getty Images, Inc.
(Grade 4/Unit 2)
Prairie rattlesnake, © W. Perry Conway/Corbis
(Grade 4/Unit 1)
Precambrian fossils, © Phil Degginger/Bruce Coleman
Inc.
(Grade 3/Unit 4)
Project photo #1, © K12 Inc.
(Grade 5/Unit 2)
Project photo #2, © K12 Inc.
(Grade 5/Unit 2)
Project photo #3, © K12 Inc.
(Grade 5/Unit 2)
Project photo #4, © K12 Inc.
(Grade 5/Unit 2)
Provence cricket, © Dennis Johnson; Papilio/Corbis
(Grade 4/Unit 1)
Python hatchlings, © J. McDonald/Visuals Unlimited
(Grade 3/Unit 2)
Quart container, © K12 Inc.
(Grade 3/Unit 5)
Red fox eating mouse, © Tom Brakefield/Corbis
(Grade 4/Unit 1)
Red-eared turtle, © Bruce Coleman Inc.
(Grade 3/Unit 2)
Red-tailed hawk, © Getty Images, Inc.
(Grade 4/Unit 1)
Redwood trees, © Jim Zuckerman/Corbis
(Grade 5/Unit 2)
Redwood/ferns, © Getty Images, Inc.
(Grade 4/Unit 1)
Reptile sunning (lizard), © Getty Images, Inc.
(Grade 3/Unit 2)
Reservoir and dam, © Mark N. Boulton/Bruce Coleman
Inc.
(Grade 5/Unit 1)
Reservoir with dam, © Mark N. Boulton/Bruce Coleman
Inc.
(Grade 5/Unit 1)
Reuse pond, © Getty Images, Inc.
(Grade 5/Unit 1)
Reuse reservoir and dam, © Mark N. Boulton/Bruce
Coleman Inc.
(Grade 5/Unit 1)
Riptide warning sign, © Arthur Gurmankin &
Mary Morina/Visuals Unlimited
(Grade 5/Unit 2)
Road map, © Washington State Government
(Grade 5/Unit 1)
Robin at nest with eggs, © Tom Silver/Corbis
(Grade 3/Unit 2)
Robin chicks, © Jeff Foott/Bruce Coleman Inc.
(Grade 4/Unit 1)
Robin with catepillars, © Rolf Kopfle/Bruce Coleman
Inc.
(Grade 3/Unit 2)
Rolling waves in open ocean, © Getty Images, Inc.
(Grade 5/Unit 2)
Salt marsh, © Getty Images, Inc.
(Grade 5/Unit 2)
Sample study plot, © Galen Rowell/Corbis
(Grade 4/Unit 2)
Sandstone block, © Hubert Stadler/Corbis
(Grade 3/Unit 4)
Sandy soil, © Larry Stepanowicz/Visuals Unlimited
(Grade 5/Unit 1)
Sea dragon, © Kike Calvo-V&W/Bruce Coleman
Inc.
(Grade 5/Unit 2)
Sea ice, © Getty Images, Inc.
(Grade 5/Unit 2)
Sea otter eating sea urchin, © Jeff Foott/Bruce
Coleman Inc.
(Grade 4/Unit 2)
Sea star, © Villoch-V&W/Bruce Coleman Inc.
(Grade 5/Unit 2)
Sea urchin (crop), © Ron Sefton/Bruce Coleman
Inc.
(Grade 5/Unit 2)
Sedimentary rock (sandstone), © A.J. Copley/Visuals
Unlimited
(Grade 5/Unit 1)
Sedimentary rock formation, © Wolfgang Kaehler/Corbis
(Grade 3/Unit 4)
Seeing-eye dog at work, © Reuters NewMedia Inc./Corbis
(Grade 4/Unit 2)
Skate, © John Giustina/Bruce Coleman Inc.
(Grade 3/Unit 2)
Skunk, © W. Perry Conway/Corbis
(Grade 4/Unit 2)
Sky with cumulous clouds, © Getty Images, Inc.
(Grade 3/Unit 5)
Smoking factory, © Getty Images, Inc.
(Grade 4/Unit 1)
Snake eating frog eggs, © Michael & Patricia
Fogden/Corbis
(Grade 3/Unit 3)
Snake with fangs showing, © Daniel J. Lyons/Bruce
Coleman Inc.
(Grade 4/Unit 2)
Sorting laundry, © K12 Inc.
(Grade 4/Unit 3)
Sprinkler , © Getty Images, Inc.
(Grade 5/Unit 2)
Squirrel (full body mammal), © Curt & Cary
Given/West Stock, Inc.
(Grade 3/Unit 2)
Star barnacle, © Norman Owen Tomalin/Bruce Coleman
Inc.
(Grade 4/Unit 2)
Starfish , © Bob & Clara Calhoun/Bruce Coleman
Inc.
(Grade 3/Unit 3)
Starfish opening mussel, © Richard Mariscal/Bruce
Coleman Inc.
(Grade 3/Unit 3)
Steep hillside, parallel drainage, © Yann Arthus-Bertrand/Corbis
(Grade 5/Unit 1)
Steep mountain valley, © Getty Images, Inc.
(Grade 5/Unit 1)
Stinging nettle, © Ken Wilson/Corbis
(Grade 4/Unit 2)
Stingray, © Colla-V&W/Bruce Coleman Inc.
(Grade 3/Unit 2)
Stormpipe drainage, © Ed Boettcher/Corbis
(Grade 5/Unit 1)
Stratus clouds, © Charles O'Rear/Corbis
(Grade 3/Unit 1)
Sun, © Getty Images, Inc.
(Grade 4/Unit 1)
Sun on black background, © Getty Images, Inc.
(Grade 4/Unit 1)
Swamp with bald cypress, © Larry Mulvehill/Corbis
(Grade 5/Unit 1)
Swamp with birds, © Peter Davey/Bruce Coleman
Inc.
(Grade 5/Unit 1)
Swimming pool, © Jeff Greenberg/Visuals Unlimited
(Grade 3/Unit 5)
Tadpole, © Jane Burton/Bruce Coleman Inc.
(Grade 3/Unit 2)
Tapeworm, © Wally Eberhart/Visuals Unlimited
(Grade 4/Unit 2)
Temperate deciduous forest, © Getty Images, Inc.
(Grade 3/Unit 3)
Termite mound, © Chris Hellier/Corbis
(Grade 4/Unit 2)
Thanksgiving dinner, © Corbis
(Grade 4/Unit 1)
Thermometer, © David Newman/Visuals Unlimited
(Grade 3/Unit 1)
Three Gorges before damming, © Keren Su/Corbis
(Grade 5/Unit 1)
Three Gorges dam construction, © Liu Ligun/Corbis
(Grade 5/Unit 1)
Tick, © Joe McDonald/Corbis
(Grade 4/Unit 2)
Tidal electric plant, © Danilo G. Donadoni/Bruce
Coleman Inc.
(Grade 5/Unit 2)
Tide pool with sea stars, © Ron Sefton/Bruce Coleman
Inc.
(Grade 5/Unit 2)
Topo. map with symbols, © U.S. Geological Service
(Grade 5/Unit 1)
Topographic map, © U.S. Geological Service
(Grade 5/Unit 1)
Tortoise, © Getty Images, Inc.
(Grade 3/Unit 2)
Tractor plowing field/seagulls, © Gunter Marx/Corbis
(Grade 4/Unit 2)
Tree rings, © Doug Wilson/Corbis
(Grade 3/Unit 4)
Trees in random distribution, © Getty Images,
Inc.
(Grade 4/Unit 2)
Trilobyte cluster, © Kevin Schafer/Corbis
(Grade 3/Unit 4)
Tropical fish, © Getty Images, Inc.
(Grade 4/Unit 1)
Tropical rainforest, © Mark Taylor-Warren Photographic/Bruce
Coleman Inc.
(Grade 3/Unit 3)
Tsunami damage, © NOAA
(Grade 5/Unit 2)
Tundra, © John Swedbe/Bruce Coleman Inc.
(Grade 3/Unit 3)
Turkey vulture eating opposum, © Arthur Morris/Visuals
Unlimited
(Grade 4/Unit 1)
Unevenly mixed laundry, © K12 Inc.
(Grade 4/Unit 3)
Unit Opener: colored liquids, © Larry Stepanowicz/Visuals
Unlimited
(Grade 3/Unit 5)
Unit Opener: dino fossils, © James L. Amos/Corbis
(Grade 3/Unit 4)
Unit Opener: insects eating, © Peter Johnson/Corbis
(Grade 4/Unit 2)
,Unit Opener: tidal electric plant, © Danilo G. Donadoni/Bruce Coleman Inc.
Unit Opener: waves, © Getty Images, Inc.
(Grade 5/Unit 2)
Very flat land, © Getty Images, Inc.
(Grade 5/Unit 1)
Warm thunderstorm, © Mark Karrass/Corbis
(Grade 3/Unit 1)
Water pollution, © Getty Images, Inc.
(Grade 5/Unit 1)
Water pouring from faucet, © Gregg Otto/Visuals
Unlimited
(Grade 3/Unit 5)
Water recreation scene, © Getty Images, Inc.
(Grade 5/Unit 1)
Water striders, © Gary Zahm/Bruce Coleman Inc.
(Grade 3/Unit 3)
Watering hole, © Michael Fogden/Bruce Coleman
Inc.
(Grade 4/Unit 1)
Waves crashing on rocks, © Getty Images, Inc.
(Grade 5/Unit 2)
Waves eroding seashore house, © James R. Mccullagh/Visuals
Unlimited
(Grade 5/Unit 2)
Waves gently lapping, © Getty Images, Inc.
(Grade 5/Unit 2)
Waxy coating experiment, © K12 Inc.
(Grade 3/Unit 3)
Weather balloon, © NOAA
(Grade 3/Unit 1)
Weather radar - Doppler, © NOAA
(Grade 3/Unit 1)
Weather satellite, © Science VU/NASA/NOAA
(Grade 3/Unit 1)
Weather vane, © Terry Gleason/Visuals Unlimited
(Grade 3/Unit 1)
Wetland being destroyed, © Marc Epstein/Visuals
Unlimited
(Grade 5/Unit 1)
Wetland being restored, © Marc Epstein/Visuals
Unlimited
(Grade 5/Unit 1)
Whale jumping, © Getty Images, Inc.
(Grade 4/Unit 1)
Whale with barnacles, © George D. Lepp/Corbis
(Grade 4/Unit 2)
White wolf in snow, © Getty Images, Inc.
(Grade 3/Unit 3)
Wolf eating deer, © Joe McDonald/Visuals Unlimited
(Grade 4/Unit 1)
Wolf eating deer, © Joe McDonald/Visuals Unlimited
(Grade 4/Unit 1)
Wolf eating deer, © D. Robert & Lorri Franz/Corbis
(Grade 4/Unit 2)
Wooden toy block, © Getty Images, Inc.
(Grade 3/Unit 5)
Yellowstone hot spring in winter, © Joe McDonald/Visuals
Unlimited
(Grade 3/Unit 5)
Young rabbit, © Erwin & Peggy Bauer/Bruce
Coleman Inc.
(Grade 4/Unit 1)