This applet is a good possible exercise in an intro to statistics or data analysis class about how data can ?obstruct itself?. The impacts of meteors of different sizes are modeled and with enough impacts older craters are completely obstructed. The user is asked to estimate the number of impacts. The applet could be used as a demo or as a homework assignment with a written response. It seems easy to pick up for anyone who has some enthusiasm for meteor craters (I do).