I'm working with the same shapes as lessons 1 & 2, but since circles were dominant in lesson 2, I made the triangles dominant in this lesson. I used a split complementary color scheme again, this time with red, orange (my 2 warms) and blue-green (my cool). And I chose a vertical layout. In order to add interest to the negative space, I pieced the background, and in order to stay with the vertical layout, I pieced it as vertical strips. I had all the triangles pointing up for the same reason.