DD11 started asking questions really young, so I've had some practice answering stuff on the fly. When I realized recently that a) her and her friends were maturing rapidly and b) she was getting more and more exposed to older children in her classes (she's starting high school level classes next year), I figured we'd better get a little more organized. We got a book called _It's Perfectly Normal_. It covers ABSOLUTELY EVERYTHING and may have topics that some families aren't comfortable with. We passed it along to her and she did a masterful job of self-censoring (by skimming the sections she wasn't comfortable with). She also asked me some questions that indicated she'd had some misapprehensions that I was happy to help her correct.