By watching its users learn languages – and make mistakes – in real time, Duolingo is developing a unique view of education

After months spent away from the language-learning app Duolingo, my level-five French skills were in decline. The “food” category was particularly threatened, coded red (for danger) with just one “strength bar” remaining. I clicked it, and was asked to translate: Je mange un repas. No problem. “I eat…” Wait, what was repas? My mind drifted to arepas, the Colombian snack. Defeated, I Google Translated. A meal! I should have intuited this from the English “repast”. But, in the moment, I forgot.

Learning is forgetting; or, more accurately, it’s virtually forgetting that we know something, but then being able to magically retrieve it when called upon. As Ulrich Boser, author of Learn Better, suggested to me, the human mind is not simply a computer; we will forget things, at a fairly predictable rate. So should I have simply drilled French food vocabulary every morning over my petits déjenuers? No, Boser says. The best thing “is to learn a word right when you’re about to forget it”. With each instance of effortful relearning, you remember longer [ . . . ]

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