NASA Education is a great resource for teachers featuring tons of educational materials that can be used in the classroom.
If you like game based learning, you can try out their free massively multiplayer online video game Moonbase Alpha. The game is set in the future of 2035 where mankind has started settling in the Solar System. Players take on the role of an exploration team member who work together to restore critical systems and oxygen flow after a meteor strike cripples a solar array and life support equipment. Available resources include an interactive command center, lunar rover, mobile robotic repair units and a fully-stocked equipment shed. Sponsored by NASA Learning Technologies, the STEM-learning game infuses real science, technology, engineering, mathematics and physics content throughout the game universe.
NASA have also released an IPad App, Rocket Science 101. Check out the screenshots below.