Each cell has a simple picture or cartoon the kids draw themselves, based on his model on the board. Some are more elaborate than these; some kids use colored pens to make them more particular. My colleague tells me that some kids do much more elaborate versions of his cartoons, too.
This is not an easy thing to replicate on a computer. Most computer companies make you pay extra for even simple drawing or paint programs. Programs like Illustrator and graphic design programs often require tablets or other hardware to work them well. And while my colleague would be the first to admit that he has virtually no drawing talent at all, he does give kids extra points for including the drawing on their quizzes, tests, and exams. “Art,” he would say, “is as important a thinking skill as writing.” And I agree.
Are there some cheap/free ways of transferring this to a digital environment? of wikifying it, so that many students can contribute to the same drawing, improving them and redesigning them and flagging them? Could his students create a database of such imagery, complete with not only their drawings but also photographs? I don’t know.
But I suspect it’s an important part of a digital education — learning to think visually as well as digitally, and learning to think collaboratively and contextually, as well as individually.