The difference in Causation and Correlation

Check out this Khan video: https://www.khanacademy.org/math/probability/regression/regression-correlation/v/correlation-and-causality  (note...you may have to create a free account @ www.khanacademy.org before viewing the link)  Khan provides an example of how correlation does not imply causality.  As you watch it, think about possible "lurking variables" that might be present.