I have always thought that sex ed and statistics should be the same course. There's no better way to show how vital stats is to your every day life than to look at statistics. Probabilities are so easy to misunderstand, and there are a lot that go into understanding the outcomes of sexual activity.
There's a ton I didn't get into here...like that a common trap is that, in a pinch, one might have unprotected sex with no negative outcome, and that makes it /feel/ much safer for future times. Which, I think, is a common trap people fall into.
There's also the fact that a 2% chance sounds pretty tiny, but it really does mean that, on average, if you have 50 couples using condoms perfectly, one of them is going to get pregnant in any given year. That's gonna seem weird and surprising and improbable and unfair to that couple, but statistically, it's exactly what we expected. Probabilities eventually collapse into reality, and then that couple no longer has a 2% chance of probability, they have a 100% chance, because they're pregnant, and everyone else has a 0% chance.
Being one of the two percent isn't that weird.