How To Write A Letter To Your Instructor . (last name) as befits their advanced degree and expertise. When you close your letter, be sure to choose an appropriate sendoff as well. How To Write Thank You Letter To Teacher How To Wiki from howtowiki.net Type sincerely, and skip three line spaces. I was a completely changed person until i met you on the first day of my college. It should be formal, demonstrate professionalism in the letter.