Archive for December 7, 2020

Dijkstra’s Truths about Computing Education Aren’t: The many kinds of programming

ACM Turing Award laureate Edsger Dijkstra had several popular pieces about computer science education. I did my Blog@CACM post on one of these (see post here), “On the cruelty of really teaching computer science,” which may be the most-cited computing education paper ever. Modern learning sciences and computing education research have shown him to be mostly wrong. Dijkstra encouraged us to avoid metaphor in learning the “radical novelty” of computing, which we now know is likely impossible. Instead, the study of metaphor in computing education gives us new insights into how we learn and teach about programming. So far, I’m not aware of any evidence of anyone teaching or learning CS without metaphor.

After my Blog@CACM post, I learned on Twitter about Briana Bettin’s dissertation about metaphors in CS (see link here). Briana considers the potential damage from Dijkstra’s essay on computing education. How many CS teachers think that analogy and metaphors are bad, citing Dijkstra, when the reality is that they are critical?

The second most popular of his computing education essays is “How do we tell truths that might hurt?” (See link here). This essay is known for zingers like:

It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.

He goes on to critique those who use social science methods and anthropomorphic terms when describing computing. He’s wrong about those, too (as I described in the Blog@CACM post), but I’ll just take up the Basic comment here.

Today, we can consider Dijkstra’s comments in light of research on brain plasticity (see example article here). It wasn’t until 2002 that we had evidence of how even adult brains can grow and reorganize their neural networks. We can always learn and regenerate, even as adults. Changing minds is always hard. The way to achieve change is through motivating change — being able to show that change is in the person’s best interest (see example here). Maybe people stick with Basic (or for me, with HyperTalk and Smalltalk) because the options aren’t obviously better enough to overcome inertia. The onus isn’t on the adult learner to change. It’s on the teacher to motivate change.

There are computer scientists, like Dijkstra, who believe that innate differences separate those who can program from those who can not, a difference that is sometimes called the “Geek Gene.” An interview with Donald Knuth (another Turing Award laureate) last year quoted him saying that only one person in 50 will “groove with programming” (see interview here). We have a lot of evidence that there is no Geek Gene (see this blog post here), i.e., we have note yet identified innate differences that prevent someone from learning to program. Good teaching overcomes many innate differences (see blog post here making this argument).

Of course, there are innate differences between people, but that fact doesn’t have to limit who can program. Computers are the most flexible medium that humans have ever created. To argue that only a small percentage of people can “groove with programming” or that learning a specific programming language “mentally mutilates” is to define programming in a very narrow way. There are lots of activities that are programming. Remember that most Scratch programs have only Forever loops (if any loops at all), and Bootstrap:Algebra doesn’t have students write structures to control repetition. Students are still programming in Scratch and Bootstrap:Algebra. Maybe only one in 50 will be able to read and understand all of Knuth’s The Art of Computer Programming (I’m not one of those), and maybe people who programmed in Basic are unlikely to delve into Dijkstra’s ideas about concurrent and distributed programming (that’s me again). Let’s accept a wide range of abilities and interests (and endpoints) without denigrating those who will learn and work differently.

December 7, 2020 at 7:00 am 6 comments


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