My kids love to draw but on car trips it can get messy to have paper, crayons and a lap desk in the back seat of the car. Then I found these small travel friendly Doodle Pro drawing boards from Fisher Price.

They are about the size of a book and their pen is attached - so nothing to lose! The kids love drawing messages to each other and playing the "guess what I drew" game as we drive around. They fit in the seat pocket and don't make a mess. Check them out - they tend to be around $5 or $6.