Talking to some friends, I was asked to explain the answer to the [Monty Hall problem][1]; they were having some trouble because whoever explained it to them didn't do a very good job.  

<sub>#Humblebrag</sub> I was able to explain it in under 30 seconds to most people (winning on staying is 1/3; winning on switching is 2/3 because it's based on losing the first pick, which is a 2/3); but some people just didn't understand....is there any sure-fire method of teaching the answer to people?

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Note: This question is not being asked about a math class per se, but is probably equally applicable to the classroom setting as it is to a group of friends.


  [1]: http://en.wikipedia.org/wiki/Monty_Hall_problem