Duolingo Founder On Why Online Lectures Are Not The Future Of Education

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Answers by Luis Von Ahn, Co-Founder and CEO of Duolingo and reCAPTCHA, computer science professor at CMU, on Quora.

I'm not a huge fan of MOOCs as they exist today. Live lectures typically suck, and watching them online makes them even worse. Even if we were to solve all the practical problems of watching these videos by giving everyone access to high-speed internet to enable proper streaming, by ensuring the sound is recorded well, or even going farther to make the content of lectures themselves more lively with film crews, screenwriters and actors, I think the approach is fundamentally wrong.
Classroom lectures are an offline solution to a problem that doesn't need to exist online. Before the industrial revolution, most education happened through the apprenticeship model. If you wanted to learn how to become a butcher, you'd become the apprentice of a butcher and learn everything you could from them. As the need arose to educate more and more people and to standardize what everybody knew, we figured that we could get economies of scale by putting 20, 50, or even 200 people in a room to listen to a lecture. Yes, these 30 people may come in with different amounts of background knowledge, and some may be smarter than others, but treating them all the same was a major innovation because it allowed the global educational system to scale and produce today's workforce. With technology, however, we have other ways to provide scalable access to education.
We know personalized one-to-one tutors produce significantly better outcomes than classroom lectures. One of the most famous results in educational psychology is "Bloom's 2 Sigma Problem," which shows that the average student tutored one-to-one performs two standard deviations better than students who learn via conventional classroom methods - that is, they perform better than 98% of the students in the control class! And this makes sense: teachers typically aim the lecture at some sort of "median student," which means that those above the median are not learning very efficiently, and those below are often confused.
Instead of making crappy recordings of something known to be suboptimal, we should be scaling and automating the best known teaching method: one-to-one tutors. This is what we're trying to do with Duolingo by attributing the following 3 characteristics to our teaching method:
  • Active, not passive. Instead of falling asleep while listening to a monotone lecture, Duolingo users learn by doing. Daydreaming is impossible in a context where you're required to interact to move forward.
  • Personalized. Because users learn by answering exercises every step of the way, we get a signal about how well they're learning. For example, we can tell if somebody always messes up verb conjugations in the past tense, if they can read but not understand the spoken language, or even if every time they see the word for "chicken" they take an extra 500 milliseconds to answer. We use all of this information (from more than 6 billion exercises per month) to generate unique lessons for each user.
  • Fun. Duolingo was designed to feel like a game from the very start. Students have to pass levels in order to unlock new skills, they can earn virtual currency to "buy" virtual goods, etc. MOOCs typically have horrible retention rates, whereas Duolingo doesn't, and it's largely because people like playing games.
Even though Duolingo only teaches one subject (foreign languages), it has more active users than all the major MOOC platforms combined - and they teach hundreds of subjects!


A: I'm not a believer in MOOCs but the way people "prove" their education is definitely going to change. This is one of the things we thought about when we decided to launch Duolingo Test Center to allow people to boost their resumes with a low-cost, 20-minute English exam that can be taken from anywhere.


A: It's an excellent school for computer science and technology in general, and therefore it's very nerdy. There is also a huge emphasis on practical skills, which makes CMU graduates be pretty ready for jobs. While at Google and at Duolingo, I've hired a number of fresh grads from top engineering schools, and it's always amazing how CMU grads are always ready out of the box, whereas those from other schools need a few months to get up to speed.

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