[jrd259]

> Triangular shapes are quite rare in human spaces (I don't have any in my house)

Triangles are essential in low-weight rigid structures. Look at any exposed steel construction around you (a bridge, perhaps) and you will see many triangles. The utility poles and streetlights in my neighbourhood use triangles. Unless your house has a flat root, the upper most floor is likely composed of triangles (called trusses) that you can't see because they are hidden. (They would be easy to spot in barn.) Even the desk I am sitting at now has triangles to ensure the legs don't collapse if the desk is shoved sideways. If you happen to live in a seismically active place, you would likely see triangular bracing on many buildings. And finally if you (or your kids) have even done one of those engineering challenges in school where you have to make a tall, load-bearing and light-weight structure on a budget you likely used triangles. Triangles are everywhere, if you learn to see them.

And as for the main point of this post - one reason to learn to draw is that it forces you to really see what you are drawing. Drawing from your imagination is no substitute.