I bought this book for my daughter when she was younger and it was wonderful (she is 18 now). I still recommend it to friends. I read the whole book first (and learned a few things myself!) then had a talk with her and gave her the book to read. She wasn't ready for the whole thing at once, it is a lot to take in, but read it in bits and pieces. She didn't have many questions because it gave such straight-forward simple answers to each subject. Every now and then I would ask her how her reading was going and we would talk about it. She used the book as a reference for a few years, then we passed it on to a friend who's daughter was ready for it & they loved it also. Good luck!
M.
I almost forgot, something I did when my daughter got to the section on periods - I gave her a few pads and tampons to check out (not use) but look at, take apart and see what they are made of, whatever she wanted to do with them so she was just as comfortable with the tools as the information.