One of my standard questions I like to ask strangers that is designed to tell me something about a person is, "Did you have especially interesting or memorable teachers during your school years?" What is really sad is when the person cannot think of a single teacher during all their schooling who stood out as memorable or interesting! Those who have had no stand-out teacher in all their years of being a student makes me feel exceptionally lucky. These teachers below are only some of the highlights...
There was that Spanish teacher who put up with me sleeping in her class in first period in middle school who did not mind that she had to repeat her question to me once she woke me up. She began by teaching the class songs, which had my heart right off. It was also OK with her if you came up with a different way to say the same thing on a language test, which isn't allowed these days.
Then there was the middle school art teacher who, after teaching me how to enter art contests and win them, sat me down and said, "You could be a great artist, if you wanted to do that. Not just a popular artist, not just a famous artist, but a great artist." With his help, I won $4000. in art contest awards - a tidy sum in 1968!
There was the high school history teacher who, by assigning me an event in the Civil War era and then having me research that one event in multiple history books - he taught me about point of view, bias, inflationary language, how a conqueror changes history documentation, how persuasive language works in newscasting, advertising, etc. etc. I'd have to say that was the most useful class of any I ever had, with the exception of learning how to read.
Then there was the college professor scholar from Taiwan who, after giving me credit for a class he was teaching in the I Ching, decided he would see how I was at learning Chinese - just for fun - in the three weeks left of the quarter we had left. He strung together the broken apart elements of very complex Mandarin characters by telling a story about how the history of the meaning of the parts of that character were related. It was only later that I realized he had been teaching me at a breakneck pace of 100 characters a week - and he made it completely easy to remember! (Of course, I've forgotten all of it forty years later.) It was one of the regrets of my life that the temptation of a full college scholarship I had received made me unable to travel back to Taiwan with him to teach English and complete my studies of Chinese. When I met him I observed that he seemed to change himself around to reach specific students, who were so self-involved that they never realized what a shape-shifter he was or the apparent inconsistency of how he presented himself. In one afternoon, he presented himself as a joking fool, an authority, a political refugee, a data mine, or a friendly, grandfatherly, absent-minded professor. At that time I was about to choose a particular affectation of how to present myself, being afraid that it was some form of character dishonesty to present myself inconsistently. When I told him what I'd observed in his shape-shifting ways that afternoon, he replied, "It must be that you have this characteristic in yourself, which I believe is the rapport of good teaching."
A Chinese saying: "The best compliment to an excellent teacher is to teach another." Have taught upwards of 3000 people how to juggle three items when I used to have a business making juggling balls. I still teach people to juggle. The way someone learns and unlearns says quite a bit about who they are. So I teach people to juggle partly in order to get to know someone. Sometimes I'll use the process of learning an unfamiliar skill such as juggling to draw parallels in learning another skill - Alexander Technique - which is part of the way I make a living. Alexander Technique is a subject I teach for the love of it, and because of the value I've gotten from it. A flexible attitude of continual learning can be a form of enlightenment. I never tire of giving people that first lesson in Alexander Technique - because even though it's a skill akin to the devotion of learning a musical instrument, I keep wondering if someone in that first lesson could get the whole thing, in a flash of epiphany.
Another reason I teach is the same reason I love to listen to improvisational music - I love to be around discovery when it's happening.
As has been mentioned, I also teach in order to know my subject better. Using my sharpened and sensitive observation skill has got to be another one of the biggest thrills for me - especially when I can making someone aware of something about themselves they never noticed previously that turns out to be extremely useful for them. Some of learning is uncovering what the person senses they already know innately, but have somehow forgotten and have become dulled to sensing from habitual repetition. Learning to unlearn what is unnecessary has the most delightful effectiveness - and it's so elegant.
It doesn't matter to me whether I'm the teacher or the learner, but sometimes it's easier to play the part of the learner. I once put a relationship back together that was on it's way to falling apart by choosing the most enjoyable and conflict-free situation as a "standing date." It was being the learner and my partner being the teacher at a skill we could do daily.
But the most enjoyable part of teaching - for me - is to simplify the subject, to not merely repeat the way I was taught. I LOVE to innovate ways to communicate the subject so that my students can learn it faster, easier and more thoroughly than I did.