This girl wanted a flat roof but found that the cardboard pieces kept sinking in. So, she modified her design to make a triangular roof.
Another wanted a circular roof but the bulge wouldn't stay in place, so she made a flat roof instead and reinforced it with second piece of cardboard.
Finally, this girl wanted an opening to come out of a wall, so she thought she would build a wall and cut through. However, she realized she could build two short walls then add two doors that opened up to connect to another building.