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5 Minutes with Luis von Ahn

Luis von Ahn

Photo by Brian Kaldorf

Sky chats with the CEO and co-founder of Duolingo, an online platform that promises its users the ability to learn a language faster than by other means.

Left: Von Ahn at Duolingo headquarters in Pittsburgh.


In mid-2012, crowdsourcing pioneer Luis von Ahn, a professor of computer science at Carnegie Mellon University who hails from Guatemala City, launched Duolingo, an online platform that promises its users the ability to learn a language faster than by other means. It now has 38 million users worldwide. In February, the company pulled in $20 million in additional funding and is poised to tackle a new area: language certification.

SKY: Why does the Duolingo model for learning languages work so well?

VON AHN: Because we have so many users, we can do experiments to figure out how to best teach a language. For example, for the next 50,000 people who sign up, half of them we teach plurals before adjectives, the other half we teach adjectives before plurals. Then we figure out which ones learn better.

The main thing is that [students] are very active. Compare it to sitting in a classroom, which is mostly passive. On Duolingo, you’re always doing something, and that’s better for learning. When we were starting Duolingo, we looked at books on how to teach languages; we were trying to find out how best to teach a language. And it’s funny because these books are similar to books on diets where they all contradict each other.

What makes Duolingo’s business model unique?

The most important thing to note is that it really is free. When we started, we had to figure out how to monetize and finance the whole thing. We came up with one way, which is this idea of doing translations [for clients].

For example, CNN writes all of their news in English, then they send it to us. Some of our students, in order to practice English, choose to translate CNN into their native language. Then we send the translation to CNN, and they pay us.

Is there someone reviewing the translations?

There’s not. But just the combination of students looking at each other’s translations and voting on them is good enough . . . . We do translations for CNN, and it’s good enough for them.

The main idea is that people are very motivated to do a good job because they’re trying to learn. But also the fact that there are many people doing it means that they’re correcting each other’s mistakes; I think that’s what gets it done.

What about speaking?

We have speaking exercises on Duolingo where you speak and [the program] tells you if you’ve said it correctly or not. I think we need to have more of that. But Duolingo does have a very intelligent speech analyzer.

What’s ahead for Duolingo?

To apply to a U.S. university . . . or to work at a multinational corporation, you have to take a standardized test to prove you know English. The problem with these tests is that they’re very expensive. They’re also very cumbersome, because you have to go to a testing center and they don’t exist in every city.

We thought that was ridiculous, so we have a new app. You can take a standardized test that can certify your knowledge of a language—in particular, English. It costs only $20, as opposed to $250. You can do it from home, and you can do it whenever you want.

I think that a lot of education over the next 20 years is going to be delivered through smartphones. The way I see it, things like Duolingo are the beginning of a huge shift in how a good fraction of the world is going to be entirely educated.

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