Stick or Switch
http://nlvm.usu.edu/en/nav/frames_asid_117_g_3_t_5.html?from=category_g_3_t_5.html

This program is a math version of the old game show, “Let’s Make a Deal” in which students have the choice of one of three doors, but behind only one of them is the grand prize. The object of the program is to showcase that by staying with your initial choice throughout the game (not switching your pick), you have lowered your probability of winning. The greater probability of winning is when students switch their picks after the first door is revealed. This program is centered on discovery based learning and potential for stimulating discussion on probability.