I was asked to paint an height scale in a little boy's room. The kid really loves animals, specially lions and flamingos. The idea was to have the animals all on top of each other in a big pile, and then the kid can measure himself next to the animals.
(he is now as tall as a pig and a snake he tells people)
The wall space I could use was next to his crib and I got a fairly big space to work with.