When I was 10, my older brother’s friend explained screwing to me. He said you do it 'til it starts to fizz and foam, and then you’re done. This was after we had found a used condom on the street.
My first serious girlfriend told me she had her first period at church camp. Nobody had told her what to expect. She thought she was dying. By the time we were dating, she had most of it figured out, but she still thought a girl could not get pregnant unless she had an orgasm during sex.
When I was in high school, I knew a guy who was sure babies were born anally. I told him he was mistaken, and he got really angry about; wanted to fight me over it. He apparently thought if he could thump me, that would make him right.
Many folks I knew in high school believed that Coitus Interruptus was an effective birth control method. Some of them were proved wrong.
If you’re wondering if all these kids flunked Sex Ed, there wasn’t any. I finished high school in 1967. Girls who got pregnant had to leave school. Our zoology teacher gave a very sketchy outline of human reproduction. Someone brought up the rhythm method of birth control. The teacher said he could discuss that after class, but he could be fired for teaching it.