Here are some awesome websites that can be a great help to your students:
Biomes - Great Web Sites with Overviews and Details
http://kids.nceas.ucsb.edu/biomes/index.html
http://www.blueplanetbiomes.org/world_biomes.htm
http://www.worldbiomes.com/default.htm
http://www.windows2universe.org/earth/ecosystems.html
http://www.ri.net/schools/Smithfield/biomes/
Others:
http://www.cotf.edu/ete/modules/msese/earthsysflr/biomes.html
http://chalk.richmond.edu/education/projects/webunits/biomes/biomes.html
http://www.kidcyber.com.au/topics/biomes.htm
http://www.world-builders.org/lessons/less/biomes/introbiomes.html
http://www.ucmp.berkeley.edu/exhibits/biomes/index.php
http://www.srl.caltech.edu/personnel/krubal/rainforest/serve_home.html
http://www.thewildclassroom.com/biomes/index.html