DearTeacher:
How time flies! i have finished my primary school study and will go further to realize my dream.But wherever i go , i never forgot what you have taught me before.you know i'm a naughty boy so you pay more attention to me,including both my study and life.Now,I've decided to write you a small note, thanking you for your help. I enjoyed being taught by you immensely; you are an excellent teacher and have inspired me to continue learning with an open and positive mind. I appreciate all your hard work.At the same time i promise that i will try my best to improve myself and don't let you down in the middle school.i'm sure one day you will be proud of me as usual.Once again, thank you so much for your time, expertise and patience!
yours