Where we live 11 is half way through middle school; they start high school at 13. The puberty video was mandatory after school last year when he was 10. We have attempted basic talks about sexuality for the last 2 years, because older girls in the neighborhood were pressuring the boys to date the younger girls (and literally pinning them to the ground trying to get them to kiss). My son's best friend's mom caught the kids playing spin the bottle and truth or dare when he was 9 and his friend was 8. We had a talk then about those things not being appropriate for kids his age and left it up to him if he wanted to explore that again when he was a teenager. He's pretty much uninterested in dating or hearing about sex and I'm not pressuring him, but I am waiting and watching for that to change.
As for 10 being still a child, I agree, but children are sexual beings too. Toddlers masturbate because it feels good and calms them; that doesn't stop as children get older, we just correct them about when and where it is appropriate to "scratch". And if you really think that 10 is too young to be going through puberty, tell that to the 9 nine year olds who gave birth the year my son was born and that was in good old conservative Kansas.