yeah, teaching math is difficult, but i don't envy any teacher's job. i, honestly, think that english teachers have it the roughest. would you want to read 100 crappy essays every other week or so? that's a huge investment in time outside of the school day.
alot of math is memorization, but at the higher levels (lower ones too) it is really about understanding. that was a difficult thing for me to adjust to because i learned math from teachers who emphasized memorization (like most of us on the board) but it is a different focus now.