Teachers teach people who don't know the answer yet. So they aren't wrong when you teach them. They will (gladly) accept the knowledge.

Once they know the answer, it gets more difficult to convince them that the answer they know is incorrect.

For more advanced students, those with preconceived ideas, teachers use a refutational style of teaching. It's not the same as argumentation because the goal is to find an appropriate bridge from one model (the preconceived, naive model) to another model (the one being taught). It works by pointing out a fascinating explanatory limitation in the naive model and then showing the students how the better model deals with said limitations.