I rarely make my little kindergartners spend 3 weeks on one art project (I think this was a first!), but it was so worth it! The first day, we used tempera cakes, and painted the whole paper in sunset colors. The second day, We talked about shapes, and the difference between rectangles and squares. We painted all of our buildings with black liquid tempera. I told the students to make big, tall rectangles for their buildings. The last day, we reviewed the difference between rectangles and squares (a square is a kind of rectangle, but not all rectangles are squares!), and made the windows with yellow construction paper. The students made strips of yellow paper, and cut the strips into squares. I know that a lot (most, actually) of these windows are really rectangles, and not squares, but they completely understood the concept, and the difference between the tall, skinny buildings and the (mostly) square windows is pretty clear.
Overall, I am really happy with the results.