GM's educational website explains the IC engine and much more

General Motors' GMability Education website aims to educate children in grades K-12 about automobiles, including careers, environmental impact, and technology.  One of the best parts is their interactive walk-through of a four-stroke engine. Yea, it's basic, but everyone has to start somewhere. This page is geared towards children of middle-school age, but my guess is that a lot of adults could learn a thing or two from it. Overall, I think the site is an excellent resource, and I'm especially impressed with the part directed towards those in grades 9-12. Those in the educational field would be doing their students a favor by exposing them to this material for a few days, as the impact of automobiles (positive and negative) on our society continues to increase, and the kids of today will be soon be the adults faced with creating the solutions of tomorrow.