The reason she ended up being swept into the little group receiving the periods info was that she is in a mixed age class (8-13 yr olds), is near the top of the class in ability and hangs out with the 12-13 yr olds by inclination. These 12-13 yr olds are very natural and unspoiled and do not spend their time discussing makeup and boys (no pressure there, they are just far more interested in making dens) and because they spend their days with boys, are not all that impressed by them. Most of the parents are like-minded as far as sex goes. A few years ago however, a parent caused a furore by explaining everything in gruesome detail, using dolls to explain positions etc, to her 8 yr old son. Said 8 yr old found it extremely funny and proceeded to relay it to the rest of the school. Cue several weeks of sexualised behaviour. Then it all died down and they went back to trading conkers and building dens. Of course the knowledge exists in the school. It's just that in the absence of any positive reinforcement for it, they are really not all that interested at such a young age.
What I meant by the violence/sex thing is that people seem to view violence as more acceptable fare than sex (which I think is completely skewed). Mostly the film classification board does a good job (although witness Secret Window, with Jonny Depp, which contains quite horrendous violence- people being brained with shovels, killed with screwdrivers- but is classified a 12) but a great many people do not respect the recommendations. Even more so when it comes to video games (most 11yr olds in the country own or have played GTA, which I find appalling).
This means that children are being exposed to topics at ages when they cannot handle them intellectually or emotionally, be it violence or sexual themes. And the exposure to violence being deemed more acceptable than exposure to sex, this means that as we lower and sexualise childhood, there are people out there exposing their children to violence at increasingly and even younger ages. (witness my tosser ex BIL, who thought the Jurassic Park trilogy a perfect present for his 4 yr old's birthday).
If you asked around your 8 yr old's friends, it's my betting you would find quite a few who had seen 15 certificates, and some who had seen 18s- usually horror films. I find this unacceptable and bordering on child abuse as it gives the children in question a totally skewed idea of what adulthood and the world are. Remember that children do not get their information from as many sources as adults- every piece of knowledge may well be a new one, and every nugget counts. If a child is seeing 18 certificate films on a fairly regular basis, before he or she has laid down solid moral and philosophical foundations, I challenge anyone to say it does not negatively affect them.
Sex education can never in my view be divorced from the emotional and relationship issues linked to it, which in fact are far more important, but are given way less coverage than the mechanics in the classroom.