NASA Glenn Research Center's Learning Technologies K-12 Program: Educational Bookmarks

NASA Educational Sites features various NASA educational sites.
Biodiversity.
Botany.
Dinosaur Sites. More great stuff for the younger kids.
Fish. Our gilled friends on the net.
Education Resources (General).
Government Resources.
Mathematics Sites featuring interactive applications.
Miscellaneous Science Links: lots of links to a wide variety of sites.
Natural History Museums on the Web.
Physics on the Internet.
Planet and Astronomy. Links to sites with images, data, and much more.
Rain Forest Links.
Science Starters: great places for teachers to begin learning about Science on the Internet
Social Studies, Art, and Literature Links.
Volcanoes. Terrific volcano sites for pre-high school students.
Schools on the Web.