I have been using Duolingo for a few months to brush up my Spanish. I have generally found it to be pretty useful and a significant improvement over my strategy was to listen to the news in Spanish. So I was interested to see a report on the effectiveness of Duolingo.
Even though most people enrolled in the study did not actually spent much time using DuoLingo (only a handful managed more than 30 hours in two months), there was a statistically significant improvement. How much improvement? The report estimates that a person with no prior knowledge of Spanish would be able to place into 2nd-semester Spanish after 34 hours with Duolingo.
Reasons for sketicism
While this is certainly good to see, Duolingo goes a bit far in concluding that this means Duolingo is more effective than a university. It might be true, but these aren't the kind of data you would want to show it. What we would want to know is how much the participants in this study would have learned if they had taken one semester of college Spanish. I doubt the answer is "exactly enough to place into 2nd-Semester Spanish on the study's placement test."One reason is that placement tests are designed to tell you whether someone has enough background to take a class, not whether they know exactly as much as the typical student starting that class. A second reason is that the study population is very different from your typical undergrad. In fact, nearly 3/4 of them had graduated from college already, and over 1/4 had a graduate degree. These are people who are highly experienced at education and who have been very successful, and either reason might make you expect them to learn faster than your typical college freshman. Then there's the fact that the study doesn't seem to control for whether they are using any other methods to learn Spanish at the same time (like taking a class).
I suppose my main reason for being skeptical is that while I find Duolingo incredibly useful for learning nouns and adjectives and for practicing what I already know, I've found it less useful in terms of learning grammar or learning verbs. Grammar is not explicitly taught at all (you're suppose to work out the rules of grammar from seeing example sentences). There are a lot of Spanish verbs with irregular endings, and Duolingo gives you no information about those (except what you might glean from seeing an example sentence with such a verb).
Perhaps this is closer to how children learn (though not really -- Duolingo is all about translation, and generally children don't learn their first language by learning how to translate it into another language!), but I suspect there's a reason that language classes the world over explicitly teach you grammar rules. Babies might not need it, but adults seem to.
What Duolingo is good for
This doesn't mean I've got it in for Duolingo. As I said, I've been using it and intend to keep on using it. Much of Duolingo consists of trying to create new sentences in Spanish and then getting feedback on whether you did it right or not. This is fantastic practice, maybe even better than what you'd get in an immersion environment (in which you create sentences but don't always get feedback), and I highly recommend it to anyone trying to revive moribund language skills or as an addition to an ongoing course of study. I just don't see it standing all by itself.
The other useful tidbit from this study: Most people who started using Duolingo quit, and quit quickly. Which is a reminder that the limiting factor in language learning is not what textbook or website you use, but your own dedication.
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