The Ketchup Experiment! Kid friendly site with lots of neat experiments! It has one that makes a rocket out of a film canister, which would be good for an grade space unit, but it has to many kid friendly expiriments. Great site for any science teacher.
DIY: Bubble recipe and refill station. Love the idea of reusing plastic cups from restaurants as the containers. Keep the bubble solution confined to one big refill container, and no worries about leaky, yucky containers hiding all over the house!
This Water Bottle Rocket is an awesome science experiment for kids! Interactive learning activities like this Water Bottle Rocket are the most entertaining educational crafts for kids, since they get to see science in action.