They were encouraged to show overlapping in the picture to make the jungle appear deep and full. We brainstormed a list of things that you might see in a jungle, including monkeys, tigers, snakes, fruits, flowers, vines, and lots of different kinds of leaves.
I originally found this lesson here: http://www.artforsmallhands.com/2011/04/in-style-of-henri-rousseau.html
Mrs. Brown's sample painting of a Rousseau style jungle