Sometimes when kids make outdoor scenes I notice what I call "Lollypop Trees" and "Doorknob Trees". This lesson helps kids think about what trees really look like and was designed by Mary Krench of Snyder Elementary. She showed it to me when I student taught there many moons ago. It's a great lesson because it helps kids think about what trees really look like and the parts of a tree: trunk, roots, branches, sticks, leaves, etc.
The idea is to start with the letter Y. At the end of the Y, make two smaller Y's. At the end of those, make smaller Y's. You get the idea. The y's get smaller and smaller. Then we add groups of leaves using impressionist style dabs of color. It's a lot easier than trying to draw and paint each individual leaf.
I like this project because it gives students something specific to do, yet each autumn landscape turns out very different.