@hj @sim well, yeah, sex is a topic that's tricky, i would say. it's probably harmful for children to have sex with other people, but it is still important for schools to include education on sexual knowledge, and e.g. masturbation (i would say that i did it since kindergarten, but without realizing what it is, until middle school.), how to have safe sex, what is sexual harassment and what to do if you encounter one, etc. while i was in middle school, i got taught some very shallow topics on puberty, but that's it. when i entered university, i met a student group who does sex ed to frosh and to high school seniors. still very basic, but it's better than nothing.

given that sex is still a "forbidden" topic in so many societies, i doubt there will be a lot of progress in the near future. i hope there will be, though. and again simply imposing an age limit on sexual materials does not help children become prepared for sexual stuff they might encounter either now or in the future -- only proper education will do.