The Peterman Pod
Harvard Professor: CS50, What Matters More Than CS, Lecturing Well | David J Malan
11 May 2026
Chapter 1: What is the main topic discussed in this episode?
I don't want to get into a whole internet fight here, but... This is David Malan.
Chapter 2: How did David Malan get into computer science?
He's a Harvard professor famous for transforming CS50 into a world-class online computer science course. How do you keep people engaged for a three-hour lecture?
I think a lot of it honestly comes from a place of insecurity. Like, I really don't want to be the one on stage in front of a bored audience.
I'm curious what you would say to someone that has that mindset that you don't need to actually know how the computer works.
If you're going to call yourself an engineer, you should be understanding everything that's happening among those layers.
We also discussed how AI is impacting cheating and enrollment.
It's harder for us now to hand to the administrative board of Harvard or the Honor Council, so to speak, a smoking gun.
Maybe programming will be useless in the future. Here's the full episode.
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Chapter 3: What makes a great lecture in computer science?
You posted this photo of your first assignment in CS50, not as the teacher, but as the student actually, under Brian Kernaghan. What was your experience like getting into computer science?
Yeah, it's a really good question.
Chapter 4: Why is engagement important in education?
So I was that problem set. My first Hello World program was in September of 1996 when I first stepped foot in a class called CS50. I was a sophomore at the time and hadn't honestly gotten up the nerve until sophomore year to even consider taking the class. Like when I came into college,
first year, and this is a story I tell at the very start of CS50 most years, I really gravitated toward fields that were more familiar, more comfortable for me. And I share with students that I really liked constitutional law. That was my favorite class in high school. And I figured that meant when you get to college, I should probably major or concentrate, as we say at Harvard, in government.
And so for the first year, year and a half, I was heads down focused on
Chapter 5: What is the rationale for starting CS50 with C?
studying government. But when I finally got up the nerve to like follow some friends, I think, into the CS50 classroom that day, when this very well-reputed computer scientist, Brian Kernaghan, was at the helm for just that one year, I was totally hooked. And it was the first time in like 19 years that homework was fun.
So much so that when the week's problem sets or assignments would come out, I would look forward to going back to my dorm on Friday evenings and to work through the night on my CS50 problem sets. So I felt like that was a sign that I'm supposed to study computer science.
And I saw on that assignment, it says minus two. And there's a little note there that I actually couldn't quite make out.
Chapter 6: How is AI impacting education and academic integrity?
Looking back now as the teacher, why did you get a minus two there?
It was something stupid and very easily redressable, but I did not start off computer science or CS50 on the best foot. I got minus two out of probably two points on Hello World.
I actually, I transcribed it and I tried to compile your program and it didn't compile. Interesting. Okay.
So I'm just three now, thanks. 30 years later.
Actually, I was able to compile. It's kind of interesting. But you have to like kind of force the compiler to do your bidding. It's like void main. And you're supposed to be like int main typically.
Typically now, it has since been standardized in C99, which was, in my defense, a version of C that did not exist in 1996.
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Chapter 7: What are the differences between college and online education?
And nowadays we use C11 or newer in CS50. So you probably had default compiler settings on that did not like that old fashioned main signature.
Chapter 8: What is the most challenging concept for students in CS50?
In my defense, that part was correct in 1996.
What was the story behind you going from a student to the teacher eventually?
I had an opportunity my senior year of college to teach an introductory course in computer science at Harvard's Extension School, which is the continuing ed program largely for adults.
The course was literally called Introduction to Computers and the Internet, because in 1999, we were still in the habit of introducing people to computers and the internet, as opposed to taking it for granted more so nowadays. And it was me in a room full of hundred or so adults. I was easily the youngest person in the room at like 21 years old.
The story I usually share is that that was the first and last time I wore suspenders because I was so determined to project being older, even though I was still just a senior. But that really whet my appetite in turn, not only for more computer science, even though that was very introductory and more technology focused, for teaching.
Over the next few years, I realized that doors would be closed to me if I wanted to teach at a place like Harvard College. And I eventually returned to Harvard to do my PhD for five years in computer science. And then in 2007, when I was finishing up, the former professor, my own advisor, was moving on to be dean of the school. And so there was this vacancy at the helm of CS50.
And I somehow talked my way into the job. They were interested in having a senior professor. faculty member take over the course. I guess they weren't able to find someone that first year, so I was meant to fill in for just one year until they found someone else, and that was somehow 19 years ago.
When you took over CS50, it feels like the course completely changed. When you got into it, was your first thought, I want to take this online and kind of make all these major changes, or was that a process over time?
very much a process. And so what people see now is really a evolution of the class as opposed to some overnight revolution, so to speak. The online aspect really started with Harvard Extension School since I was fortunate, right place, right time, to be teaching that Extension School course my senior year when distance education, so to speak, was becoming a thing in my
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