ABSTRACT
Usually there is no way for a college teacher to know if two students in a new class have the same birthday. If we assume that we are talking about a regular non-leap year, there are 365 possible birthdays. If we further suppose that all 365 birthdays are equally likely for any individual student, then depending on the size of the class it may seem unusual for two of the students to have the same birthday. How do we know if something that happens is something unusual or something we should have expected? This activity may demonstrate (with any luck) that something that seems surprising to most of us is not really that unusual.
