I don’t know where my son learned about writing letters (day care? TV?), but I’d say for his first attempt, he nailed it.
We just returned from a weekend with the grandparents where he was spoiled beyond belief. To try to balance out the expectations of get-get-getting, I suggested we write thank you notes. He started dictating. This is what he said to write to grandma:
I hope I will see you soon.
I miss you a lot.
I like all the presents you hide around the house.
(Nate: age almost-4)