This was a lesson I did with second graders two years ago that I wanted to share because it was a big hit.
The project had two parts. The first part was a color mixing study and investigation into analogous colors.
The students chose a set of analogous colors that represented fall foliage colors. We talked about how analogous colors are three "neighbor" colors on the color wheel and sometimes use the rhyme "three colors in a row, just like winning tic tac tow". The students printed large dots using corks dipped in tempera paint.
We studied the work of Roy Lichtenstein (which is why we included the dot patterning) and Andy Warhol and discussed what the phrase "Pop Art" means.
The other part of the project was based on observational drawing. The students observed the leaves, and drew in pencil and then traced in black pen. They had to cut the contour of the leaf carefully and create a composition with their background when they glue-stick'ed them on.