We don't eat much Halloween candy around here. First of all, Max can't eat any of it, and since I don't usually buy candy, the kids usually forget about eating it after Halloween. Instead, we do science projects with it. Last year, we made models of molecules, and this year we had two days of experiment mania. Most of our ideas came from the Candy Experiments website. We messed around with density (a huge hit), looking for the floating "s" from Skittles, tested for acid, and melted lots of different candies in the toaster oven.
Before we broke out the beakers I had the kids sort their candies and record the data, then decide on broader categories to put them in and graph the results. Who knew you could get so many lessons from Halloween treats?