‘Night and Day’: Harvard Students React to CS50 Without Longtime Instructor David Malan

Students enrolled in Computer Science 50: “Introduction to Computer Science” this semester said they missed the lecturing style of course instructor David J. Malan ’99, whose sabbatical this fall has left the course with a new lecturer and an overhauled structure.

Now taught by computer science professor Henry H. Leitner, the course is being held in a new location — lecture hall B of Zimmer Hall, rather than the historic Sanders Theatre. It meets biweekly on Monday and Wednesday for an hour and fifteen minutes, instead of one weekly lecture lasting two and a half hours.

Leitner was one of several rotating instructors to teach CS50 before Malan took over the course in 2007.

Rayan A. Azhari ’30, a current student in the course, said he missed the level of detail in Malan’s lectures.

“If you’ve seen Malan’s lectures on YouTube, and you compare them to Leitner’s lectures now, it just feels like Malan went a lot more in depth, and he had a certain enthusiasm when it came to actually teaching the material,” he said.

“If you compare the two and their teaching styles, I feel like it’s more so night and day,” Azhari added.

William K. Thai ’30, also a student in the course, similarly pointed to the difference between Malan and Leitner’s lecturing style, though he said he appreciated aspects of Leitner’s approach.

“It’s a little bit different, since I know Malan had a very theatrical style, but I think Leitner brings a lot of maturity to the subject of computer science,” Thai said. “He isn’t exactly flashy, but he’s very thorough in explaining concepts. He’s also a very visual learner. He always is constantly writing stuff on the blackboard.”

But Thai added that he wished students had more opportunities to participate in lectures.

“Something that I do wish was implemented is that I remember Malan did a lot of audience work,” Thai said. “He always had people come up to the front to do demonstrations, but Leitner doesn’t really do that.”

Malan, who has taught the class for nearly two decades, is widely known for overhauling CS50. More than 7 million people have enrolled in an official online version of the course available to non-Harvard affiliates, and the course materials are used in high schools across the country.

Carlos A. Salais ’28, who took the course when it was still being taught by Malan, described it as “an experience.”

“It felt like it was really high production value,” Salais said. “He recorded all the lectures, it was like going in on the set of a TV show.”

Current students also raised concerns about the difficulty of the course this semester.

Azhari said that the content students faced on problem sets was more difficult than what was presented in lectures and section — and that the course was not as “beginner friendly” as it is described.

But some students said they enjoyed the course’s current format.

“I don’t take the old class as a benchmark, but I think it’s really interesting,” Trevor B. Hou ’30 said. “I enjoy the class a lot. I’ve learned a lot about CS, especially C, and I think overall, at least with my experience in programming, I did learn a lot of new things.”

Kevin Zhang ’30 said he appreciated the course’s biweekly meeting time.

“I’m in favor of shorter classes and doing it two times a week,” Zhang said. “I think there’s some aspects of the class that were lost with Malan not teaching it anymore, but I think they’re still retaining a good portion.”

In response to a request for comment, Leitner wrote that independent learning was a key part of his approach to teaching.

“I want students not only to understand the concepts presented in lectures, but also to apply them, reason through unfamiliar problems, and become more independent problem-solvers. Developing those skills inevitably involves some learning outside the classroom,” he wrote.

“At the same time, students need a solid foundation and the support to succeed, which is why we provide a strong teaching staff and a wealth of additional pedagogical resources on the course website,” Leitner added.

Malan supported Leitner’s approach to out-of-class learning.

“If students are finding that much of their learning is happening outside of class, whilst wrestling with challenging problem sets, then I think the course is in good hands!” he wrote in a statement.

Malan will return to teaching CS50 in the spring.