Are you sure it was a 'birds and bees' talk? Many parents get hung up on sex-ed thinking their child will come home talking about the 'ins and outs' (sorry about the phrase, no pun intended!) of sex and how babies are made. Most sex-ed classes in primary schools are really 'growing up talks' which inform the children about the correct terminology for body parts and how their body will change. Being a teacher myself, I know only too well the importance of teaching this to children BEFORE it begins to happen which EVERY year has happened in Year 4 to at least a couple of children.
Don't get me wrong, I am not 'for' teaching children about the mechanics and reasons behind sex but at an early age, children should know it is a penis and vagina and not use the slang terms. The more the see and hear terms like this being used in a sensible and responsible manner, the less likely the are to seek misguided information from friends and magazines and get into trouble.
I'm a big believer that the more we talk to children about their bodies (even when they enquire at an early age), the less likely they are to think it's 'dirty' or 'naughty' or 'out of bounds' and seek more information and are thus confronted with information and images that encourage promiscuity and under-age sex.
After all, we have one of the worst underage sex and pregnancy rates in the developed world. As a nation, too many of us are embarrassed to talk to our kids about this, hence the reason why they too get embarrassed but are eager for knowledge and without discussing it or guiding our kids, we risk them finding out by other means which maybe a route we'd prefer them not to take!