OK, so I make the tree at AES, and the students make the Kandinsky circles.Based on Kandinsky Circles. Might be a fun classroom project. Teacher cuts out (or paints! Students create the circles for the branches.
Watercolour triangles let students paint paper with watercolors, wet on wet, similar colors. Let dry and cut into triangles. Students pick triangles and glue down randomly, leaving white around each one. Maybe try with black or other color background?