When I was first approached by painter friend Coni Grant to do a demo for her adult painting class, I felt honored - to begin with. I was soon apprehensive about doing a hasty painting that would be crap, and in front of witnesses no less.
That initial demonstration was very educational- for me especially. It had been decades since I taught painting and drawing. I knew that I had accumulated a lot of knowledge about painting but it had been extremely internalized over many, many years. It was all in my head.
I happily discovered that I could communicate this internal jumble to other people and in a way that they could understand, (or were they just being polite?)
Before one demonstration, my wife and I were channel surfing and happened upon a program where a painter was doing a painting video. He basically just said out loud what his process was- what he was doing, with what tool or brush, using such and such color mixed with such and such other color.
So that is one sure way to communicate painting dynamics- just start blabbing away about each and every little thing that you are doing.
Here is a picture of a painting demonstration that I did for Coni's class.