[math-fun] Re: Error in Scientific American math puzzle.

The way I usually teach this topic in introductory probability classes is that (under assumptions that need to be made explicit but are very reasonable), the question "A family has two children, at least one of whom is a boy; what is the probability that both are boys?" and "A family has two children, at least one of whom is a boy named Bartholomew; what is the probability that both are boys?" have different answers. I learned this gimmick (giving the boy a name) from Charles Grinstead or Peter Doyle (I'm not sure which). Jim Propp