Do you think sex education is necessary to boys & girls at secondary level?

We live in a world where kids find out about sex on the internet, or they hear about it from TV, even though their parents are against it. It's hard to keep this as a secret from your child, cause he can also learn about it at school. If nobody tells him/her that sex is not good for a kid, then he will definitely want to try it. Girls get pregnant at 12, so sexual education is necessary.