Explaining Differential Gears with YouTube Videos

I've always had a hard time visualizing how a differential works. This hampers my ability to explain the concept to my students. Here are some videos that may help others who, like me, are differentially impaired.


How Differential Gears Work (instructional film from the 30's)



LEGO - Differential Gear





[Via Neatorama: This is the post that got me started...]