Personally, I really do beleive that Sex Ed should be taught at home and in schools, but there are several problems with the at home part. I know that VERY few parents feel capable sharing that type of information with thier children, or it is a taboo in their religion to eve really discuss. My mom was raised Roman Catholic, and my father was raised Muslim. They never talked about sex with me. My mom's full discussion with me was that it was pleasant and that I should use birth control, to hell with what the catholic church said about it. My dad seems inclined to continue pretending it isn't happening to his daughter. :P
I do think, however, my schools did a really respectable and thorough job in discussing sex with the class, however, I do think that for OUR time, when not many children at our age knew that sex existed, it was a little too early. I do feel, though, that in these times, that's when it should start, from a purely anatomical and scientific perspective, and that until middle school, that should be the entirety of it. from there, adding to the knowledge of what sex is, and what one's options are pertaining to sex is a good step. I think children should be encouraged in school to discuss sex with their parents and in context of their religious values, but in a positive way, not in a "having sex makes you a slut" kind of way.
I am personally thankful for the fact that I had so many other outlets to question when the right time for sex was, and that in High School, the kids were encouraged to visit www.plannedparenthood.com
(please take the link out if this isn't "okay") I do suggest that parents look through that site as well as there are some good materials available for teaching your children more.
Honestly, if it weren't for the planned parenthood website, or the great teachings we had at school (more than just abstinence, though this was considered prime) I would never have known how to take care of myself when I was raped, or what to do, where to go, and get tested, and while thankfully, I didn't get an STD from it, or become pregnant, I could have, and not known what was what.