> The most difficult task was to teach them things they were previously taught incorrectly.

That is an easy thing to fix. If they take everything the teacher tells them at face value, they are bound to to repeat silly errors (and worse, biases,) in the teachers knowledge. If you teach them that the teacher might err (including you), then it is so much easier for you to demonstrate how they know wrong. Even better, if you fail at something while teaching (everybody do), they will be more likely to correct you, and you will learn something from them.