[johnohara]

To teach is to learn. -- Japanese Proverb

To teach is to learn twice. -- Joseph Joubert

I taught CS to high school students for ten years. I found the most welcome questions were always the ones I had not considered. Especially if it meant admitting you did not know. There is something in that admission that builds student confidence. Preparing an explanation and going over it with the class awards a tacit accolade to them all that tends to inspire more questions.

[zarify]

Agreed. I'm coming up to a decade of teaching CS in high school as well. The best times are when I don't know the answer to something I've been asked (and considering my classes go down the rabbit hole with topics pretty frequently this happens a fair bit :) since not only do I have to go learn about it I also have to learn how best to explain it and ascertain understanding of it in my students. The best moments are finding a really great way of relaying a difficult concept and having my kids have that "ahah" moment.[1]

I also started studying Karate about 5 years ago, and being given lower grade classes to teach helped my understanding of my own technique immensely (sadly it did nothing to alleviate the fact I was a creaky old man of 31 when I started ;P).

[1] One of the problems of teaching a set level of students though is you tend to stagnate at that level without your own side projects, which get less attention because of the time factor. That's about the only regret I have with teaching as a profession.