Showing appreciation to a teacher is an important part of giving back to the educators that have influenced your life. Whether you're writing in favor of a teacher to a committee, or writing directly to them, a well-crafted appreciation letter is imperative. Remember the basics of grammar and sentence construction, but also address directly what you feel are their strong suits and the reason they are successful in the classroom.
Brainstorm ideas to cover in the letter. Make a list of topics, anecdotes or examples you might use to illustrate the teacher's classroom demeanor, or what was particularly effective about their approach.
Narrow your focus to a few items on the list. Choose examples or highlight personal feelings that truly illustrate your appreciation and the teacher's abilities. State when you had the teacher in class, for what subjects and for how long.
Write a one to two page rough draft utilizing your chosen approach. Concentrate on the clarity of your descriptions and your message. Keep in mind what audience the letter is intended for.
Edit your piece for content and language. Try to make your appreciation direct, so that you highlight your experience and the teacher's merits -- without bogging the letter down. Print the final copy once you think it's ready.