I came across a news item in which school children from the age of 5 were to be imparted sex education (explicit) to raise awareness regarding Aids/drugs. While the need to raise awareness regarding these social evils and diseases cannot be overemphasized, we disagree with some of the methods employed for the same.
Sex education is a difficult topic to handle for most parents and teachers. So what is Islam's take on it. There is an excellent article by Malik Mujahid Saheb (may Allah reward him), in which he gives tips to parents about sex education and another one in which he urges parents to get involved. May Allah guide us all Amin !
Posted by Arshad
on Thursday, November 16, 2006. 
Very apt title for this topic. Protecting their innocence is the priority. I dont see a problem of explaining things to children early (ages 8-9)provided I explain it from a biological perpective first and then a psychological one. But more important is to inform them about how not to be mislead and misguided by peer pressure and free media.