http://www.k12science.org/currichome.html - Listing of online projects.
http://www.field-trips.org/sci/endanger/index.htm - Endangered Species: Click on teacher resource link and then start the project link.
http://www.field-trips.org/sci/tornado/index.htm - Tornadoes: Click on teacher resource link and then start the project link.
http://teacher.scholastic.com/maven/ - Interactive math games students can play online for basic skill reinforcement.
http://teacher.scholastic.com/activities/explorer/native_americans/index.asp - Native American Cultures: participate in the online project or use the site to gather data.
http://teacher.scholastic.com/activities/explorer/ecosystems/index.htm - Endangered Ecosystems: follow Costa Rican caterpillars or Mexican Wild Cats.
http://teacher.scholastic.com/activities/wwatch/ - Weather Watch: Projects include Hurricanes, Winter Storms, and Tornadoes.
http://birds.cornell.edu/cfw - Classroom Feeder Watch: Report back to Cornell University about what is happening at your feeder.