What’s generally good for you vs what meets a need: Balancing explicit instruction vs problem/project-based learning in computer science classes

Lauren Margulieux has posted another of her exceptionally interesting journal article summaries (see post here). Her post summarizes recent article asking which is more effective: Direct instruction or learning through problem-solving-first (like in project-based learning or problem-based learning — or just about any introductory computer science course in any school anywhere)? Direct instruction won by a wide margin.

Lauren points out that there are lots of conditions when problem-solving-first might make sense. In more advanced classes where students have lots of expertise, we should use a different teaching strategy than what we use in introductory classes. When the subject matter isn’t cognitively complex (e.g., memorizing vocabulary words), there is advantages to having the students try to figure it out themselves first. Neither of these conditions are true for introductory computer science.

This is an on-going discussion in computing education. Felienne Hermans had a keynote at the 2019 RStudio Conference where she made an argument for explicit direct instruction (see link here). I made an argument for direct instruction in Blog@CACM last November (see post here). Back in 2017, I recommended balancing direct instruction and projects (see post here), because projects are clearly more motivating and authentic for computer science students, while the literature suggest that direct instruction leads to better learning — even of problem-solving skills.

Lately, I’ve been thinking about this question with a health metaphor. Let me try it here:

Everybody should exercise, right? Exercise provides a wide variety of benefits (listed in a fascinating blog post from Freakonomics from this June), including cardiovascular improvements, better aging, better sleep, and less stress. But if you have a heart problem, you’re going to get treatment for that, right? If you’re having high cholesterol, you should continue to exercise (or even increase it), but you might also be prescribed a statin.  If you have a specific need (like a vitamin deficiency), you address that need.

Students in computing should work on projects. It’s authentic, it’s motivating, and there are likely a wide range of benefits. But if you want to gain specific skills, e.g., you want to achieve learning objectives, teach those directly. Don’t just assign a big project and hope that they learn the right things there. If you want to see specific improvement in specific areas, teach those. So sure, assign projects — but in balance. Meet the students’ needs AND give them opportunities to practice project skills.

And when you teach explicitly: Always, ALWAYS, ALWAYS use active learning techniques like peer instruction. It’s simply unethical to lecture without active learning.