Very interesting. I bought an Escher book with many of his drawings in the late 80s and were fascinated about them. Good that you use the method of teaching your students being able to flip between the diagrams and the formulas.

The link you gave here:

As Penrose adumbrates in this short video, his whole thinking style is visual rather than algebraic, spatial rather than symbolic.

does not work but leads me back to your own article. Can you correct that?