Kids Planet by Defenders of Wildlife.
http://www.kidsplanet.org/

Rainforest Who and Where.  3rd through 5th graders worked on this 
site soon after school began.  The Fall Scholastic Bookfair is the Reading 
Rainforest.  Students will be able to show off their knowledge of rainforest 
animals and where they reside in the rainforest structure.
http://www.amazonworld.co.uk/fun_games/whoandwhere.html

WebWeather for Kids.
http://eo.ucar.edu/webweather/

Amazon Interactive.
http://www.eduweb.com/amazon.html

Passport to Knowledge's Passport to the Rainforest.
http://passporttoknowledge.com/rainforest/main.html

A great site to help find science projects for a Science Fair.
http://www.sciencebuddies.org/

PBS-Journey into Amazonia.
http://www.pbs.org/journeyintoamazonia/

Bookfield Zoo's In Search of the Ways of Knowing Trail.
http://www.brookfieldzoo.org/pagegen/wok/index_f4.html

Rainforest Heroes-Salmon Sally's Upstream Sprint presented a major challenge 
to our 3rd through 5th graders.  It is a very realistic game with the goal 
of helping Salmon Sally get upstream through various real-life obstacles 
such as oil, logs, fisherman and bears.  The Game of the Day link leads to 
word searches and crossword puzzles.
http://rainforestheroes.com/fun/games.html

National Geographic's Plant Power.  This site did not work correctly in our 
computer lab but will help 3rd grade students with their unit on plants.
http://magma.nationalgeographic.com/ngexplorer/0604/games/game_intro.html

The Great Plant Escape.  Help solve the plant mysteries.  Great for 3rd 
graders and students studying plants.
http://www.urbanext.uiuc.edu/gpe/

Planet ARKive.
http://www.arkiveeducation.org/games.html

Animal Classification Hangman
http://www.apples4theteacher.com/hangman.html

Animals of the World
http://www.kidscom.com/games/animal/animal.html

Mendel's Peas (Genetics) for 5th graders
http://www2.edc.org/weblabs/Mendel/MendelMenu.html

Clean Sweep U.S.A.-from Keep America Beautiful.
http://www.cleansweepusa.org/

BBC's Interactive Activities for ages 4-11.  Includes science, math and 
English.
http://www.bbc.co.uk/schools/digger/

NASA's Space Place for Kids.
http://spaceplace.nasa.gov/en/kids/

Kids Club from NASA.  Has 5 different skill levels.
http://www.nasa.gov/audience/forkids/kidsclub/flash/index.html

StarChild: A Learning Center for Young Astronomers.
http://starchild.gsfc.nasa.gov/docs/StarChild/StarChild.html

BBC's Science Activities.  Choose your age level to begin.
http://www.bbc.co.uk/schools/scienceclips/index_flash.shtml

Plant Explorer (3rd grade)
http://www.naturegrid.org.uk/plant/index.html

Name the Parts of a Plant (3rd grade)
http://www.crickweb.co.uk/assets/resources/flash.php?&file=plantlabelmxhtm

Magic School Bus Habitat Game
http://www.scholastic.com/magicschoolbus/games/habitat/#

National Geographic Interactive Activities (Includes Africa 
CritterCam)
http://kids.nationalgeographic.com/Games/InteractiveAdventures

Gardening (Plants) Jigsaw Puzzles.
http://www.surfnetkids.com/games/garden-js.htm

Plants Concentration
http://www.surfnetkids.com/games/garden-c.htm

Online Science Exploratorium Activities.  Excellent!!!
http://www.exploratorium.edu/explore/online.html

Enchanted Learning Desert Biome
http://www.enchantedlearning.com/biomes/desert/desert.shtml