I've  always  enjoyed teaching.   Mainly  it  has been  a  part-time
endeavor, a small  part of whatever job I had  at the time, although
for a  few years as a  contractor I taught full-time.  I have always
taught  technical   classes  like  firewall  management   or  system
administration.

One of the things  I would do before teaching a  class for the first
time  is  that  I would  do  a  deep-dive  into  the topics  on  the
syllabus. I  was always worried someone  would ask a question  and I
wouldn't have the slightest clue what  they were talking about. So I
would study, then  study some more. If a student  asked a question I
did  not have  an answer  to,  it would  give me  something else  to
research for the next class.

In this  way I was  constantly learning  from the students,  which I
suppose  is  not an  obvious  way  to  look at  the  student-teacher
relationship. But  looking at it this  way one can see  how teaching
can be very rewarding.