BrainPOP is an educational website with hundreds of short Flash-based movies for students in grades K-12 about mathematics, technology, health, science, social studies, arts & music, and English. Most of the videos feature the site's recurring characters, Tim and Moby.
Here is a short movie that gives an overview of brainpop.
Our district's username is rhk9. Email me for the password.
BrainPOP also has an educator site that you can create your own username and password for free.
For an example of one way to use BrainPOP, please see Kelly Meyer's page for students unable to particpate in P.E.