They are also the best reinforcers of this new skill, because they usually can be counted upon to write back. Have some scratch paper nearby in case they want to make short notes about what they want to say. Have a dictionary available in case of spelling questions. A thank you note could not only contain the requisite truncated appreciation for the gift, but also a description of how the recipient plans on using it, or the fun they've already had playing with it. If something interesting happens to your child, encourage them to write about it in a letter instead of a quick phone call sufficing to relate the experience.
Young children can draw or paint a picture and dictate their thoughts to an adult.
If the child has grown used to the immediacy of email, use your scanner to send the letter when it is finished. Pen pals are all-forgiving when it comes to spelling and grammar, and can teach your child about the world. There are some real meanies out there who pose as kids and you will have to be vigilant in your protection of your child. Once children are fairly comfortable with writing to relatives and other children, they can progress to writing to people with whom they have no personal relationships. Enter the business letter.