I like to encourage my students with an occasional postcard addressed to them at home. I have chosen to mail something to their residence instead of putting a note in their locker so that the parents see as well. Besides, we all receive so little real snail mail, that it’s a treat when we do! I use their French name from school that they have chosen and when appropriate write a bit in French. The idea is that the student will have to translate that French to their parents, thus putting themselves in the limelight.
I rarely hear from the student himself, but often a parent will convey to me how much it meant to their child. My goal is to write 2 a week throughout the year. Weeks that are shorter or have trips I bypass. I also keep a google doc as a log and can see last year’s table of recipients as well. Since I generally have French language students for 3 years, keeping this kind of record is useful to me. I stock up on postcards that have a French message or picture or artwork.