Why AI will help Duolingo become as good as a human tutor
Luis von Ahn, Co-founder and CEO, Duolingo
In some ways, Luis von Ahn is an unlikely founder for a language-learning company: The entrepreneur dreamed of being a math professor from a young age. But after he invented the now-ubiquitous reCAPTCHA service and sold it to Google, the computer science professor and entrepreneur set out to create something with tangible value to its end users. He also wanted to ensure it remained free.
“A lot of people talk about education as something that brings equality to different social classes,” von Ahn says. “But I always thought that what happens in practice, especially in poor countries or regions, is that people who have money can buy themselves a really good education and therefore continue having a lot of money.”
Duolingo, intended as one solution to that problem, now boasts 60 million monthly active users who are learning 40 languages through the app’s gamified lessons. Last year, the company broadened its offerings with the launch of Duolingo Math. Earlier this year, it introduced Duolingo Max, an expansion of the original Duolingo that provides highly customized lessons powered by GPT-4. And, in keeping with its original mission, the majority of Duolingo’s users today are located outside of the United States. As a result, the company’s freemium model enables subscribers to effectively subsidize the education of users in less wealthy locales.
Von Ahn joined Scarlet Fu, Bloomberg Television and Bloomberg QuickTake host, at Bloomberg’s Global Headquarters in New York City on Tuesday, May 20, 2023 for a conversation as part of the Cornell Tech @ Bloomberg Speaker Series. He shared his experience creating a useful – if “annoying” – technology in the early 2000s, finding ways to make learning compulsive, and how advances in AI are helping Duolingo reach its goals.
Watch the full discussion:
Reconfiguring an “annoying” technology to produce value
Von Ahn was raised in Guatemala by a single mother who sent him to an American school. He says he felt lucky to learn English as a child. An early interest in computers was accidental, he says. When he was eight years old and asked his mother for a Nintendo, she got him a Commodore 64 instead. Von Ahn bought computing magazines to teach him how to use his new computer, learning to copy games by looking for hidden files and trading them with neighbors.
Despite his early interest in computers, von Ahn’s childhood dream was to become a math professor at a university, and he studied the discipline as an undergraduate at Duke. But when the entrepreneur was visiting Ph.D. programs, he became concerned about the field’s pace. “You would talk to professors and they would say, ‘Oh I’m working on a problem that hasn’t been solved in 400 years,’” says von Ahn. “I’m like, chances are you’re not going to solve it. Nor am I.”
Computer science, by comparison, was a relatively young field that was evolving at a breakneck pace. By the early 2000s, von Ahn was a first-year Ph.D. student studying computer science at Carnegie Mellon University, and a scientist from Yahoo! brought a series of problems to his class. Among the problems was the issue of spammers writing programs to quickly sign up for new email accounts using the service. Along with his Ph.D. advisor, von Ahn had the idea to have users read and input a series of squiggly letters that computers couldn’t comprehend at the time. Soon CAPTCHA was ubiquitous across the internet. Von Ahn gave it to Yahoo! for free.
A few years later, von Ahn found himself at parties explaining that he’d invented CAPTCHA. “And everyone would say, ‘I hate you, it’s so annoying,’” he recalls. “And then I started thinking, people are doing this 200 million times a day, and it takes 10 seconds. So humanity as a whole is wasting 500,000 hours every day because of this thing that I did. And I started feeling bad about it.”
Von Ahn’s eventual solution was ReCAPTCHA, which used a similar verification process to recognize patterns computers couldn’t. Through the improved test, users first helped to digitize books, then helped mapping software recognize traffic lights or bikes. He sold the service to Google in 2007.
Luis Von Ahn in conversation with Scarlet Fu of Bloomberg Television and Bloomberg Quicktake
Building a model to offer education for free
At the time ReCAPTCHA was created and sold, von Ahn was a professor of computer science at Carnegie Mellon searching for a passion project. “It’s not like I was very passionate about annoying people with distorted letters,” he says. “But I was very passionate about education.”
Along with one of his Ph.D. students, Severin Hacker, von Ahn began casting around for an education-related endeavor. They settled on building a language-learning tool, following the logic that learning a language can directly impact a person’s circumstances more than any other discipline. If a person learns math, says von Ahn, they’re still a few steps removed from applying those skills in the workforce. But “in most countries around the world, knowledge of English increases your income potential,” he says.
The first iterations of Duolingo failed, von Ahn says, because he and Hacker struggled to stay consistent. “It was too boring,” he says. “The hardest thing about learning something by yourself is staying motivated.” So the pair added progress bars, a point system, and a leaderboard. The company officially launched in 2012 and, because it was free and fun, he says, it grew quickly.
A few years after it launched, there were more people in the United States learning a language on Duolingo than there were in the country’s entire school system. But, by 2016, the company, which had so far relied solely on venture capital to fund its operations, needed to become more sustainable. It implemented a freemium model, a relative rarity in the edtech industry at that time. “It’s a very mission-driven company,” says Von Ahn. “We really want to offer education for free.”
According to Van Ahn, 92 percent of Duolingo’s users are currently on the free version of the app. But those 8 percent of customers who pay are providing around 75 percent of the company’s revenue. It creates a situation, he says, where relatively well-off people in the United States are effectively subsidizing the language education of people who live in countries like Brazil or Vietnam. “It’s like a small form of wealth redistribution,” he says, “which I really like.”
Expanding Duolingo’s gamified education model, assisted by AI
Von Ahn considers Duolingo a consumer-driven company, and is resistant to the idea that his language-learning app might expand outside of its current scope to grow its bottom line. There’s a huge market of people who want to learn languages, he says, and doesn’t believe it’s necessary to fundamentally change how Duolingo’s business is done.
But the team has made some tweaks to the app and expanded its offerings in recent years to ensure users are actually learning. One notably controversial change required users to take a more linear progression through the app’s lessons. It was intended, says Von Ahn, to prevent people from repeating easier lessons. Users “were just addicted to their streak,” he says. “And they weren’t actually learning anything.”
The team also launched Duolingo Math and started working on a Duolingo for reading music, Von Ahn says. Earlier this year, they launched Duolingo Max, a version of the language app that utilizes GPT-4.
Duolingo has been reliant on AI since the beginning, says Von Ahn, as he and his co-founder attempted to create a tool that could teach languages as well as a tutor. The original version of the app personalizes language lessons based on an individual’s weak spots and reshuffles lessons based on their progress, he says. But recent advances in generative AI have allowed the app to expand its effectiveness. Now Duolingo Max can explain to a user why they got something wrong, he says, and it’s possible to have multi-turn conversations in the app.
Von Ahn is optimistic about AI’s capacity to help Duolingo achieve its ultimate goals. “What you’ll hopefully see in the next five years,” he says, “is that we will become as good as a one-on-one language tutor.”
This article was originally published by Tech at Bloomberg.
