Buildings in one point perspective

I think teaching how to draw perspective is one of the most difficult topic. Learning the rules of perspective is a difficult task for students, and every year I need to find more effective strategies to teach this topic between art and science. I found this interesting tutorial and with 7th grade students, we have been inspired by this unusual point of view. Is as you were in the middle of a big city, in a crossroads, looking at the sky. Where is the vanishing point? In the middle of the sky, of course.

To make this drawing we drew the building with pencils and markers and then we painted the sky with watercolors. Our drawing is more simple than the one in the tutorial and we used rulers, but the results are amazing!