As we all know, learning some of the concepts in Calculus such as the Chain Rule, Quotient Rule, etc requires a lot of study and re-study. Sometimes, having a pretty good video that can be replayed can be of help. I found a great site that has spent a lot of resources developing some pretty neat videos. The site is Tutorials for the Calculus Phobe. I recommend you try a few out by going there. Dr. Brown