I just read that Ted Talks is now making animated lessons about certain subjects that teachers might want. It has just begun so there are limited movies, but the ones that are there are very interesting. It looks as if it might be a free version of Brain Pop. Certainly worth checking out. http://ed.ted.com/
I just watched the one on the atoms! Worth checking out.You can turn the videos into an assignment where the student would watch the video and then take a quiz. This can be customized by you.