Sex ed in schools? In my school there was only ONE sex ed lesson in 8th grade.
Where I live, you only can learn about sex from TV, books and the Internet. Probably they think that if they don't do sex ed, then adolescents won't start sex too soon. Well that's bullshit.
Interest in sex is awaken by hormones and instincts, NOT the knowledge about sex. And if adolescents can only learn about sex from the TV, they'll have a false imagination on it. That's why people often start sex too early and not because the sex ed.
In fact if they'd know about STDs and safe sex sooner, they'd probably wait with sex until they find the right partner and don't do it just because they're curious.

As for myself, I bought books and fortunately my mother is liberal about sex, so I could ask her about anything.
Yet I'm here with my 23 years and still being a virgin...

Abstinence until marriage doesn't make sense. If you love somebody deep from your heart, you want to give them the greatest pleasure you can. Waiting until marriage just makes the tension build up. Sex is important in a relationship, but it's not the meaning of life. And sexual incompatibility will often lead to cheating and/or divorce. And nobody suffers more from a divorce than the kid they have. So one should choose their mate very carefully and that involves compatibility in sex too. Anyway, marriage is not just a question of love.