Or, one reason why teaching is good for teachers.
I've just got to the point in Richard Feynman's autobiography where he's talking about why he loves teaching. It really resonates with me & I thought I'd share this bit with you:
If you're teaching a class, you can think about the elementary thgns that you know very well. These things are kind of fun and delightful. It doesn't do any harm to think them over again. Is there a better way to present them? Are there any new problems associated with them? The elementary things are easy to think about: if you can't think of a new thought, no harm done; what you thought about it before is good enough for the class. If you do think of something new, you're rather pleased that you have a new way of looking at it.
The questions of the stduents are often the source of new research. They often ask profound questions that I've thought about at times and then given up on so to speak, for a while. It wouldn't do me any harm to think about them again and see if I can go any further now. The students may not be able to see the thing I want to answer, or the subtleties I want to think about, but they remind me of a problem by asking questions in the neighbourhood of that problem. It's not easy to remind yourself of these things.
In a good classroom, everyone's learning.
R. Feynman (1985) Surely you're joking, Mr Feynman! Norton.