As a parent of 4 grown kids, I found that even with a good "Christian" upbringing, and a very good education on sexual matters, kids are going to do what they want anyway. Peer pressure being the biggest influence after the loose morality of the media is what drives these kids/teens. Look at who they are looking up to as idols. 

Why not just give the Health Depts. the job of sponsoring sex ed classes and then parents can choose to attend with their kids. I'm sure many parents would learn a thing or two as well.