I taught a lesson on smoking in Health class yesterday and we were talking about some of the health problems certain chemicals in cigarettes can cause. One of these health problems was damage to kidneys. My students didn't know what our kidneys do, so I explained that they filter our blood for waste and create pee. Well, one kid pipes up and says "So, if we pee blood, that's bad." To which I replied that yes, it was bad and if they ever peed blood they needed to tell a parent ASAP. Well, one girl put up her hand and said "Well, except for girls". I asked her what she meant and she said "You know, when a girl has her period. She pees blood" I replied that no, when women have their periods they don't pee blood and that we would cover that in more detail when we started sexual health next week. It blew. their. minds. MOST of the girls in the class thought that periods meant peeing blood. And, these are girls in Grade 7. They, presumably, have started, or will soon start, menstruating. Oh, and of course the boys were horrified that we were even talking about it.