How to thank a good teacher? Say if you were a graduate of ABC university, and
When you want to thank a teacher of this university because she used to help you a lot in some courses or because she has the same hobbies and interests as yours, and you want to be friends with her:


Should you just send a thank you letter to her or buy her a present?
If you choose to buy her a present, should it be a brand-named and very expensive one?
As a college instructor, the one thing that has meant the most to me in terms of thanks has been when students tell my superiors how much they enjoyed having me as an instructor. Even just an email to my boss from a former student was a very solid form of thanks. It made me look good; it also made my supervisor proud of himself for one of his lowlings having success. For me at least, this was the ultimate thanks.