NASA's Amazing Space, 6-12

http://amazing-space.stsci.edu/
Amazing Space is an online space science resource that features a set of interactive curriculum support tools, news articles written for students, homework help, and information on space science topics. A unique feature of the Amazing Space is found on the “For Educators and Developers” side where each curriculum support tool has an overview page of information designed to help teachers integrate current science into their classrooms.