A thank you note is a talisman of appreciation for another person. Simple, yet powerful .
In my classroom, we focus on gratitude by practicing the art of the handwritten note. So humble, such clout, the letter of thanks in a person's own hand.
I require students to master friendly letter form. They protest. They already thanked the field trip drivers in person. The museum docent was just doing her job. The person who organized the speech tournament was paid. But the guest speaker spent a couple hours preparing his presentation, woke up early, put on special clothes, drove 30 minutes, gave up a morning for us. We honor his gift by spending five minutes penning words of thanks. The kids can't figure out a good objection to this argument, so they dutifully write their notes.
Ah, and the letters need to be done with care. The writing straight, no crossed-out mistakes, the word "sincerely" spelled correctly. No binder paper, but real cards. Written in ink, with more than just the words "thank you," and including a few original details to make the gratitude feel personal.
The thoughtful gesture of a handwritten thank you radiates goodwill both directions. And it packs a wallop.