@ElderWendigo@MiraLazine agree to disagree, a lot of those things I was definitely taught - if not in school then at least by adults who thought it common knowledge. Especially the nosebleeds (I had them all the time as a kid, and the amount of blood I ended up swallowing is..... A lot.) and knuckle cracking (my guess - started by teachers annoyed by kids making knuckle-noises during class)
Christopher columbus was definitely taught as an "American hero" up until he wasn't.