There's a new portal for science education in town. Aptly-named and currently in its beta phase, ScienceEducation.gov is an aggregate of educational content from various federal science agencies, committed to digital learning and open participation.
Its content is conveniently sorted by grade level and includes lesson plans, curricula, classroom activities, homework help and professional development information. It also includes a very prominent front page slot for JASON Science games, including Operation: Resilient Planet and Coaster Creator. Give it a look.