7.3.1 Food Chains and Food WebsFood chains and food webs help show how energy is transferred through an ecosystem. There are three roles in an ecosystem: producers, consumers, and decomposers. As plants and animals are eaten, less and less energy gets transferred up the food chain. That's why an ecosystem needs a lot of producers to support only a few top consumers.

Create Basic Food Chains
1) http://www.harcourtschool.com/activity/food/food_menu.html
2) http://www.ecokids.ca/pub/eco_info/topics/frogs/chain_reaction/play_chainreaction.cfm
3) http://www.blue-iceberg.net/rutgersfoodweb/frameset.html