I think I mentioned this on All Things Hold Together before, but it is worth bringing up again.
Disney released all 100 episodes of Bill Nye the Science Guy on DVD. The classroom editions include a PDF file with lesson plans based on the episode, along with a short quiz.
Our library has a bunch of these and the kids love them.
I love that they come with a quiz that I can print out and include in our yearly portfolios.
I also love that the kids enjoy watching them again and again, reinforcing the concepts.
There is something wonderful about my 4-year-old asking to watch Bill Nye.
As Bill Nye says, Science rules!