Gather round children, this is going to be a good one.
My first experience with sex-ed was in year 3, yes, year 3. To a class of year 3 boys and girls they showed a video entitled "Where do babies come from?" which, through a combination of diagrams that we all laughed at and impossible to understand Southern US accents, didn't succeed in teaching us anything at all and mostly got the teachers ticked off who were silly enough to think that we'd understand or even be serious at such a presentation.
Then in year 6 came interrelate. again this was a co-ed school so in the one classroom guys had to learn about periods, girls had to learn about nocturnal emissions (WET DREAMS LOLOLOLOL). Me, I treated the whole thing as one big joke, when we were given diagrams of naked boys and girls and we had to draw on the effects of puberty I just drew horns and shit, I almost made it a game couning how many girls fainted hearing about periods. The diagrams were embarassing, the news was pretty old hat (Mind you I finally learned what a paps test is...oh the horror), the woman that came in each day of the one week long course was insufferable and thankfully I wasn't there on the final day when they showed the touted video of a woman giving birth.
Still, at least it didn't involve one evening of me sitting in church between my parents and all the other unlucky kids while the priest explained everything like what was the case with my father.