It's a bromide that teachers learn from their students. If the translation of the bromide comes to "Students impart information to their teachers of which the teachers were ignorant"
gleaned new information from those I teach, it doesn't tend to be the sort I was itching to know. (I really did not need to know that Ben Franklin's sells cap bombs. Really. Although I must admit it is in keeping with their patron's interests.) I will not deny, however, that I have learned from my students in this sense: that in looking for questions to ask them, I have had to dig deeper into certain questions than I would be likely to, left on my own.