Study: schools that give away condoms see more teen births, not fewer - Vox
Seems that no one is sure of the reasons. Not enough banana demonstrations, so to speak, is mentioned in the article.
Or is it just that thorough education on the details of sex in a high school setting is one thing, but in-school steps which appear to actually facilitate it is another, not so good idea? It's not as if condoms are not readily available, at cheap cost, for those teens who want to start a sex life. Maybe making them responsible enough to go and buy them for themselves encourages responsibility in starting a sex life, generally? Who knows.
And I hasten to add, again: does any adult really think that it is a good idea for high school students to be having a sex life at all?