We started out by reading "Monsters Love Colors" by Mike Austin and reviewed/learned how the primary colors red, yellow, and blue can be mixed together to create secondary colors (and beyond!).
After discussing this, and filling in a color mixing chart, anddddd singing the primary color song and the secondary color song (to the tune of "Are you sleeping?"), students got to experiment with primary-colored glitter liquid watercolors to paint a background for their art piece.
Mini-tangent: The song goes like this..."Primary colors, primary colors. Red, yellow, blue. Red, yellow, blue. They're primary colors, they're primary colors. Red, yellow, blue. Red, yellow, blue."The next day students started cutting out the trees that their color mixing "leaves" would hang on. Each student started out with a piece of 6"x9" black construction paper. After reviewing scissor safety, students cut a large triangle into the side of their construction paper. Once the triangle was cut, they left some place next to the triangle and cut out a "Y" shape (see diagram - I'm sure it will make more sense).
Once the base of the tree was cut out, students cut out additional rectangular shapes to be added onto their trees for branches. I made it a point to explain to my first graders that trees grow UP from the ground.. so it made more sense to have the branches pointing up instead of down. Then students glued these to their painted paper.
The next day we reviewed our primary/secondary color mixing knowledge - then students went to work creating their primary/secondary Kandinsky-esk "leaves"! The only requirement was that the leaves had to have 3 individual shapes (that composed the larger "leaf") and they had to show how to mix the featured secondary color. After my first rotation teaching this, I found that it was really effective to explain it to students like this...
They needed to cut out a big mommy and daddy primary color shape, then in the center cut out their baby secondary color (the color they would make when mixed together). We also talked about how it didn't matter which order they glued their primary color shapes down on their leaf. Red+Blue=Purple and Blue+Red=Purple... just like 1+2=3 and 2+1=3.
Overall I really like these! I've seen projects similar to this before.. but never with the specific primary/secondary color mixing leaf combinations.