Discovery Education
Discovery Education: Classroom Planetarium
Create a classroom model of the solar system while teaching about relative size of all the planets, and each planet's distance from the sun.
NASA
Nasa: For Educators
Contains many links to projects and workshops, as well as educational resources.
Other
Nasa/msu Bozeman Center for Educational Resources (Ceres) Project
The CERES Project allows the nation's classroom teachers to develop "an extensive library of on-line and interactive K-12 science education materials for teaching astronomy." The site features latest news and photos from NASA,...
NASA
Nasa: Imagine the Universe: Supernovae (Basic)
A detailed description of a supernova developing from a single massive star. There is a quiz, related links, animation, lesson plans, and an FAQ sheet available also.