Aggie, I was never a student that bothered my teachers. However, never in a million years would it have occurred to me to THANK them! On the other hand, I was speaking to a friend of mine in Italy, who is a little older than me. She said "we felt lucky because we were able to attend school at all" you see, that's the difference.

I had few great teachers, and a few mediocre teachers that did great things.
I never did any homework at home until my Algebra teacher said, homework EVERY night, and if you miss 2 nights, you fail my class. That one simple ground rule changed me from a C student to an A student. Because if you sit down to do your Algebra homework, you might as well do all the rest.
Unlike Oakleaf, I can remember all my teachers, and most of their names. I can remember the ones who were unfair, those that favored girls over boys, those who didn't like me because my last name was different from my mother's.
I have managed to contact the three of my teachers who were important to me as an adult. That was fun. You never realize how your words as a teacher are going to affect your students.
When i was a senior, a teacher said to us; "Most children of divorce end up divorced themselves" (a statistic that i am certain is true) This upset me profoundly and I made it my business to prove her wrong. And I tracked her down and told her about it.

Teachers, you have an incredible opportunity to sow seeds in our youth. You never know what rocky fields will grow a tree.