I don't think a lot of you are aware of how many children already know about things like oral sex and all sorts of other things. When I taught Sex Ed to Year 4's 30 years ago in an inner city school, I was quite taken aback about the things they discussed. Whilst I don't think you should be encouraging them to try it, if they are asking the questions, I do think that you shouldn't be shoving the subject under the carpet.
As for Anal Sex and Oral sex, some of the posters sound as if they are saying that it should always be taught as wrong. Whilst they might not float your boat, they are considered normal practises. So, at what point do you start saying that?
It is all very complex and we must get the balance right in explaining that they cannot give consent until they are 16 but also not making it sound like it is a terrible thing to do. I remember some of the normal things like male erections when they were asleep really troubling me. I didn't get the Sex Ed in school. Had I had that, instead of worrying, I would have known that is was all perfectly normal and not thinking I was married to a pervert. It's laughable now but it wasn't at the time!