Mildly Interesting

widely spread myths

That's your problem. You can't seriously argue that these myths were being taught as fact in school because they weren't. They're all myths spread by common idiots through word of mouth. Common public misconception on the facts can and does happen very independently of actual education, as evidenced by antivaccers lately. The only things you could honestly add to a list like this would be some scientific theory that has been definitively disproven or amended. Maybe something like changing training about CPR would qualify also.

But those kinds of things are boring. It's much spicier to claim that people were taught that Columbus's contemporaries thought the world was flat even though that was just an over simplified story told to 5 year olds to explain why they got out of school on Columbus Day. Meanwhile anyone that didn't sleep through trigonometry should learn that Eratosthenes showed the world was round about 1700 years before Columbus. I would believe that there are some lazy educators out there that would teach such myths as fact, but to claim that it was at all universal is silly. The whole premise of "old generations dumb, look what they believed" is just so smug and offensive. I must be getting old.