Begin your thank you note with "Dear Professor," followed by his name. This will be the greeting part of the note, and should look something like this:
"Dear Professor Johnson,"
State your reason for writing the note as being to give thanks for his assistance regarding a particular request. This request could have been a letter of recommendation that the professor wrote for you or possibly going over your research with you. It should look something like this:
"I can't thank you enough for taking a moment to write a letter of recommendation for my graduate school application. I am certain that your recommendation will be a deciding factor toward my acceptance."
Start a new paragraph and describe your admiration for another contribution from the professor during your educational career. Write a specific example of when the professor's personal teaching style helped you grasp a concept, for example. Give reference to a particular lecture that stood out in your mind as giving you an understanding of the topic he was discussing, if you choose. This second indication of gratitude makes the first one appear more sincere.
Close out the letter. Thank the professor again to end the body of the letter, then skip down two lines and write "Sincerely." Skip down two more lines and write your full name, and the year you are expected to graduate. Write your major and the current semester season and year on the next line. It should look something like this:
"Once again, I really would like to express my thanks for your time in assisting me as you have."
Sincerely,
Michael Jones, Class of 2011
Information Technology 202, Spring 2011