This is the final list they came up with:
1 - Greeting (Dear _________)
2 - Farewell (Love, From, Sincerely, etc.)
3 - Saying thank you for whatever the person did for you
4 - Asking if there is something you can do for them in return
5 - Telling them what you're going to do for them
6 - Drawing a picture
Before starting our discussion I had not envisioned going beyond the first three ideas on this list. The fourth idea expresses a beautiful sentiment and was suggested by one of my quieter students, which prompted another child to contribute #5 above. I was ready to add this last idea to our list when a third child said that you may or may not ask (or tell) the person to whom you're writing the thank you note what you might do for them in return. At this point, a lively conversation ensued about whether or not numbers four and five count in a thank you note. I suggested that we might want to put an asterisk next to numbers 1 - 3 if we agreed that they absolutely had to be in a thank you note; the other ideas would not get an asterisk because they were optional but we agreed they did enhance the quality of the note. Earlier, a fourth child had said that drawing hearts counts in a thank you note. At first, in my short sightedness, I had gently discouraged this response but in light of the unexpected turn our discussion had taken I suggested we add this to our list, as well. Everyone enthusiastically agreed.
So, now we have a list of ideas that may or may not be everyone's idea of what counts in a thank you note but that does make sense for our class. And, it makes sense not because it's right or wrong but because it was created through a collaborative conversation based on reasoned thinking by grade 2 students.