A real leaf, a piece of paper, and crayons
This is an easy way to make an image of a leaf using a real leaf, a piece of paper, and a crayon (or crayons). Find a nice leaf -- whatever your child likes is fine, but big ones that aren't too fragile work best. Put the leaf on a flat surface, like a desk or counter-top, and cover it with a piece of paper. Let your child rub his crayon on the paper directly on top of the leaf. Magically, a leaf image will appear! Collect lots of different kinds of leaves, maybe one for each kind of tree on your street, or create a lot of rubbings from one kind of leaf to make your own tree image.