While I don't endorse abstinence-only education, I would like to see how many kids actually pay attention and follow what their full (non-abstinence-only, if that's even a term) sex ed classes on a regular basis. I'm not looking for personal anecdotes, but I do know that as a teen, even fully cognizant, sometimes I said ********** it" and didn't use a condom.
What's that psychological term? Invincibility theory? It has to do with the frontal lobes not being developed all the way. Anyhoo, at that age, you simply don't think certain things could happen to you, and it's in the way the brain works. Maybe it would be best to see what kind of efforts are successful at this age, and then model sex ed, driver's ed, etc. after it.