Dear (老师的称谓）,
How are you?I hope you are well.
I am writing this letter to say thank you to you.I really appreciate what you have done for us this year.The way how you teaching students is very impressive.For example,you told us a lot of interesting stories to help us to learn those difficult English words and we did remember most of the words after listening those amazing stories.Anyways,Thanks again for everything you have done for us.
By the way,It's almost Spring Festival.Happy New Year!All the best wishes to you and your family.
Yours
Lucy