I dont remember anything that was proven false. I remember i butted heads with my history teachers constantly. Having history as my hyperfocus of my autism, and hyperactive talking from adhd, i had to correct one teacher a lot.
Saying the classic "the HRE was neither holy nore roman nore an empire" but nobody called it that back then. It was known as just "the empire". And the "holy" part was due to shenanigans with the pope, and it defenetly was an empire in the sense of span. Yes everything was autanomouse, but it was an empire by size of who swears loyalty.
I learned more that the things i back then saw as useless and "why are we being tought that" is actually really important. Example: text analysis if grammer, way of phrasing things, wether the autor clearly frames things threw choice of words, if it is a story, news article or comment