I first have my students look at Van Gogh's "Starry Night" and share anything they see in the picture. I then ask for the kinds of lines they see in the picture and introduce landscape and how artists show space with overlap.
Then the class glues their green strip along the bottom of the purple paper. We use liquid tempera to paint short vertical lines with green paint on the green paper and spiral lines with violet paint on the purple paper.
During the second class we reviewed Van Gogh's use of lines and how to show space. The class then trace three ovals onto orange paper and cut them out. We glued them overlapping the grass and each other to show space. (We also discussed why we wouldn't glue an oval in the sky not overlapping the green paper.)
We talked about how pumpkins are not smooth and the kinds of lines found on them. We then used red-orange liquid tempera to paint curved vertical lines on each pumpkin and added a brown stem on each. The kids love how beautiful their work turns out and always ask when they get to take them home. I didn't warn them their classroom teacher's love them too and usually hang them in the halls for awhile. :0)