[Your letterhead, if desired; if not, your return address]
[Date of letter-month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
As the end of this semester draws near, I want to take a moment to let you know how very much I have appreciated having you as my professor for my sociology class. I am thankful for all that I have learned through your interesting and informative classes. I am also just as appreciative of your obvious caring and concern for all of your students, including me. It has meant so much to have a professor like you. I hope our paths will cross again soon, and perhaps I will have the privilege of being your student in another class.
Thank you again-I so appreciate all that you do. Have a wonderful and relaxing break between semesters.
[Sender's first and last names]