Ever try to describe how the rear differential on a car works? Honestly, it’s a total bitch with the outcome usually ending up with confused looks by both parties involved. The above video was made by General Motors in the 1930′s and is so easy to follow that it’s painful. At first it seems like something that should be shown in an elementary school, but the more you watch it the more you’ll realize how truly easy it is to understand and more importantly, why GM produced it. If you’re a car guy or gal and always wondered what made your wheels spin, well then look no further because this little flick explains it perfectly. Wouldn’t it be great if all of life’s mysteries were so easy to explain.