Traditionalists may look aghast at CS50, Harvard’s introductory computer science course, which last year became the school’s most popular course of any kind. It’s taught by a young professor in jeans and a black T-shirt, David Malan, whose lectures are highly polished, fast-paced performances filled with props, demonstrations, and student involvement. Students aren’t required to attend, though; lectures are recorded in a slick, multi-camera format with production values that rival commercial TV, and most students watch them online. In addition to being Harvard’s No. 1 course, it’s offered simultaneously at Yale, with Malan teaching, an arrangement apparently unprecedented in the rival schools’ 318-year coexistence.
But far from being a dumbed-down sop to spoiled students, CS50 is a carefully crafted model of how to teach any subject in today’s technological and social environment. It’s extraordinarily demanding; by mid-semester, most students are spending over 12 hours a week on problem sets. If they need help, dozens of teaching assistants are available for in-person assistance 10 hours a week, far more than in traditional courses.
“There’s so much support,” says Emily Schussheim, a Yale junior who took CS50 as a freshman. “It’s also really social.” Other students have called it a phenomenon, a spectacle, a cult, and a lifestyle.
CS50 is available for free on the EdX education platform, where it has been taken by over a million students. Schussheim tells Fortune she came to college planning to major in economics, with “no real intentions” of ever taking a computer science course. Now her major is computer science and economics, and this fall she’s a teaching assistant in CS50.
A version of this article appears in the September 2019 issue of Fortune with the headline “A Crimson Phenomenon.”