Kit was in the 2nd or 3rd class of primary school when he first disagreed with his teacher. It was a biology class, or rather general studies (Sachunterricht) at that age. My son has always been tremendously interested in biology, among other things, so he constantly researched, learned, and excavated some new information. When his teacher claimed something about bats, which was according to the school books, Kit respectfully disagreed and corrected her. Her reaction was great.
She said, if he could prove his claim, she would correct her teaching. At the next class, he presented the information, and his sources, she acknowledged all of it, informed the other students, and now the whole class was up to date on that tiny bit of info. A parallel class to this one, in the same school, would have learned an incorrect piece of information. That incorrect information would have been passed on to all the children, and they would have taken it as an indisputable point-blank fact, when, in fact, it wasn't.
Kit's class also learned that authority figures can sometimes be wrong.
Some months later, or maybe another year, there was a similar situation again. Luckily, Kit always felt free to voice his objections, in a calm and objective manner and, luckily, the teachers were cool about it. They didn't let their ego get in the way of education.
There can be no shutting up when it comes to learning, there is no room for censorship. Not if you really want to find out things.