Photo: Provided by Duolingo.

A few years ago, about six months before a trip (my first) to Paris, I downloaded Duolingo in an attempt to “learn French.” I put that in quotation marks because I did not, of course, expect to become fluent or even mildly conversant in a foreign language over such a short time frame, and especially not using an app. But I did expect to learn something — anything — useful. I hoped to learn how to say “Where is the bathroom?” or “How much does this cost?” or “I want that one,” the sort of purely transactional but useful phrases a tourist needs to get around town at least somewhat politely. When I went on a class trip to China in college, I learned these three phrases, plus “hello” and “thank you,” and I remember them all today, 14 years later. Do you know why? Because they are real things people say, unlike most of the phrases I recall being taught via Duolingo.

Here is what I remember from my months of Duolingo French studies: “une pomme.” An apple. I cannot even begin to tell you how many times Duolingo had me talking about apples. And not in normal, plausible contexts — not “I’ll have an apple, please,” or “Do you want my apple?” The circumstances in which Duolingo envisioned my needing to speak about apples were either too fanciful (“The bird is eating an apple: L’oiseau mange la pomme”) or vaguely threatening (“My pocket contains an apple: Ma poche contient une pomme.” I translated apple from English to French and back again. I spoke it aloud. I typed it out when it was spoken to me. “I GET IT,” I screamed at Duolingo. “UNE POMME.”

Sure, I know how to say hello, and please, and thank you, but these are all things I’d already absorbed by living in a country that loves putting French words on pillows and T-shirts. I didn’t learn much of anything about sentence structure, because the Duolingo app doesn’t explain that to you. If coming to a language as a novice, you’ll learn largely by trial and error, which means you’ll learn by memorizing, with little context as to why sentences look the way they do. It’s hard for me to believe anyone could really learn a new language in any meaningful way with this program. But I’m not a language professor, or an expert; I am merely a crabby writer with slight Francophile tendencies. What do actual language professionals think of Duolingo?

Kerstin Cable, a language coach and host of the Fluent Show podcast, first wrote about Duolingo in 2015, criticizing it for its impractical vocabulary, its insistence upon one acceptable translation per sentence prompt, and its lack of explanation for incorrect answers, and she tells me much of this criticism still holds. “In this app,” she wrote back then, “you learn by parroting phrases, without even beginning to cover the background stories that grammar and pragmatics tell.”

But what annoys Cable most about Duolingo is the app’s own propaganda. “For a while, Duolingo told you, ‘You’re X% fluent.’ Which is one of the most insane things I’ve ever seen,” she told me, because how is fluency being defined? Duolingo doesn’t serve users that message anymore, but there are still big claims being made — one recent pop-up I got between lessons said that playing Duolingo for 34 hours was equivalent to a college semester’s worth of language instruction. But what grade will you get at the end?

Steven Sacco is a retired language professor and linguist with 40 years of experience, who now owns a consulting firm which works to develop language learning programs with multinational corporations. He has also used Duolingo to study 26 different languages, completing all available lessons for seven of them. Intrigued by Duolingo’s “34 hours” claim, he put it to the test, studying Swedish on the app for a total of 300 hours. (Most introductory university Swedish courses amount to 150 or so hours of coursework, he reasoned; 300 would be more than safe.) He then convinced the professor of UCLA’s Elementary Swedish course to let him take the final exam. He got an F.

This is not to say that Duolingo is useless; when we speak by phone early one morning, Sacco has already completed his daily Duolingo lessons. “I love the opportunity to take language lessons for free, and I can study languages anytime,” says Sacco. “I love the competition factor, where you can compete against other students.” (Duolingo allows you to add “Friends,” with whom you’ll share scores, and be ranked accordingly.)

But it is precisely some of these gamelike elements that frustrate Cable. Duolingo is “so focused on giving you rewards, like check-boxes, that it hasn’t given you a lot of chances to fail,” she told me. “And as a language learner, you have to fail. Eventually you’re going to be in front of people, sounding like an idiot. It’s part of the process.” People don’t speak like algorithms do, and it’s only in using weird, too-formal expressions in front of other people that you’ll learn the latest, best slang. (Another benefit of failing in language learning: The shame, which will never let you forget the word you meant to use.)

Duolingo’s design largely relies upon a system called “spaced repetition,” a technique in which learned information is repeated at regular (usually short) intervals. And it’s true that spaced repetition combats what’s called the “forgetting curve,” thus allowing for easier and longer-lasting memorization. Memorization can help you learn new vocabulary. But we also get worse at memorization as we age, say Richard Roberts and Roger Kreuz, psychologists and co-authors of Becoming Fluent: How Cognitive Science Can Help Adults Learn a Foreign Language. Memorization and accent come more easily to children, but adults have more tools at their disposal, say Roberts and Kreuz, like higher proficiency in our native language, and what they call “metalinguistic awareness,” or knowing how a language works. When adults expect themselves to learn effectively based on rote memorization alone, they write, they soon become demoralized, and give up.

Cable echoes these concerns. “I don’t think [using Duolingo as your only tool] is going to get you anywhere, and it’ll give you that dissatisfaction that so many people feel. It’s really frustrating.” These limitations wouldn’t be so bothersome if Duolingo itself didn’t suggest it’s all anyone needs to learn a language, which it does in loading screen messaging like “15 minutes a day can teach you a language,” or that 34 hours equals a college semester course claim. Duolingo might be good at teaching you vocab — Sacco says Duolingo provides users with more than 3000 vocab words over a given language course — but that doesn’t make it comprehensive. Duolingo “certainly isn’t going to be something I recommend to my clients in French West Africa, that they take Duolingo English to improve enough to be able to work in English,” he says. “That’s not something I’m going to advise them to do without using an immersion setting in addition.”

Cable notes that the web version of Duolingo — which I admit I did not know was a thing — provides much more in the way of grammar instruction than its much better known app counterpart, and is better at explaining why certain answers are wrong (or right). But she and Sacco agree that nothing comes close to immersion. To learn a language, says Cable, “you need habit, human contact, and you need varying resources, otherwise language learning doesn’t really go anywhere.” Sacco puts it even more bluntly: “There’s nothing but immersion, period.” But, he adds, he and his wife are considering a move to Sweden, and what resources are there if he wants to learn Swedish before the move, short of hiring a private Swedish tutor, for who knows how much money? Duolingo will have to do for the meantime. Duolingo, my enemy, you’ve defeated me yet again. Or, as the French would say: une pomme.