Understanding the Facts of Life is a good book which explains sex and puberty. It starts off by telling you about growing up and height. After that you learn about health eg muscles. Then it explains that when you reach puberty a lot of changes happen to your body like more hair and periods (for women) as well as sperm and eggs. It also explains shaving and pubic hair.

Then you learn about bras and female sex organs (and periods), then male sex organs. After that it explains sex, kissing, touching and stroking. Then it explains contraception and sexually transmitted viruses/infections eg HIV. Then it tells you all about pregnancy and babies. Afterwards it's babies' growth and development.

At the very end of the book it has a babysitters' guide. I think it is a good book and is definitely worth reading. I would give it six or maybe seven out of ten. I think the illustrations are kind of cartoons and quite fun. Also the information is quite complex with words like contraception, but there is a glossary which is a plus!

Understanding The Facts of Life (Usborne) is by Susan Meredith & Robyn Gee.