I have taught 1st graders how to write a friendly letter. I've found it helpful that they write using authentic experiences, and thank you notes are a good place to begin. We've written dozens of thank you notes to the
people of our school- janitors, cafeteria workers, and former teachers for the good work that they've done.
In the beginning, I've found it useful to number the various lines on the primary paper to assist them in formatting their papers. For example, #1 corresponds to the date, #2 corresponds to the greeting, etc. That way, they don't lose their place in copying off the board,
or forget the placement of parts of a letter when they do their work independently.
Also, we plan on writing postcards for a US postcard exchange.