Duolingo

In the beginning, it was a very similar idea to this book digitization. What can we get out of people learning a language? Can we get something useful from them? Computers cannot yet do that for us. So what we did is we actually had contracts with CNN and BuzzFeed. They would write all their news in English. And then after a certain point, we'd say, hey, you want to practice what you just learned? Here's a CNN article in English. Why don't you help us translate it to your native language?"