Duolingo claims that it is ‘the world’s best way to learn a language’. The app – which has tens of millions of users – boasts a ‘science-backed approach’ that it says ‘delivers measurable results’. I’m not convinced: it seems to me that time wasted on Duolingo would be far better spent doing almost anything else.

Busy people, of course, can’t be expected to learn languages the most efficient way: dropping everything to spend some time in a foreign country and learn by immersion. But flicking through one of those kitsch phrasebooks, or listening to a podcast in another language, slowed down to 0.5x speed if necessary, is probably more likely to help your language skills, in a way that is better tailored to your abilities and interests, than five minutes a day on Duolingo.

Yet millions have been taken in by Duolingo and its marketing gimmicks.