Think back to a more innocent time, before you knew what sex was and how it worked. You'll remember that you had no clue what two grown-ups in love did when they were alone together, but you probably had some vague ideas. It wasn't so much that we were all innocent—we were mostly just very, very confused.
Kids today actually don't know much better, even with their constant exposure to Twitter and Snapchat. They often still learn the basics in classrooms, where good schools teach comprehensive sex education. There's a lot of confusion for teachers to sort through. And it's their job to do so with a straight face, taking questions seriously.