Dear Teacher,
This is a letter that you may never get, but that does not make it any less true. We often never know our influence. Don’t forget that everything you do matters. Keep not giving up! Keep doing everything you can to reach ever student that you can. You never know how much that they need all that you say and do…even if it just making them complete assignments or retaking a test. It all matters, and it will come back to them…even if you never get to see it or hear about it!
You are awesome! The difference is being made. Keep on being relentless! And, as always, keep on teaching, Teacher!
Love, Teacher
Dear Teacher/Love Teacher 
Nice one.
Thank you!