There are courses on how to doodle.
The house I grew up in was filled with doodles from my dad. I doodle, my kids doodle. School, phonecalls, spare time, all perfect occasions to doodle. One day kid got home with a test where she had doodled at the bottom of the page. (The bottom of the test had a printed grey border with white dots) The teacher had with red written "WHY!!!!??" next to the doodle. I saw it, and said that had I been the teacher I would have written "Why not?" at every non doodled border.
Teachers like that, is probably where those courses on how to doodle are aimed at.