So, I'm from Guatemala. This is a public service announcement, that is where Guatemala is. (Laughter) Also, that is notwhere they keep the prisoners. That is called Guantanamo. (Laughter) Not the same place. So Guatemala's right below Mexico. And for the Americans in the audience, and let this sink in,because it really applies in most ways, for the Americans in the audience, you can think of it as Mexico's Mexico. (Laughter) Just like the US doesn't wantillegal immigration from Mexico, Mexico doesn't wantillegal immigration from Guatemala. It's a smaller country. It's a poor country. And well, what can I tell you, it has much better Mexican food. (Laughter) Guatemala is a very poor country. And a lot of people talk about education as something that brings equalityto different social classes. But I always saw it as the opposite,as something that brings inequality. Because what happens in practice is that people who have a lot of moneycan buy themselves a really good education and therefore continuehaving a lot of money. Whereas people who don't havevery much money barely learn how to read and write and therefore never make a lot of money. And this is especially truein poor countries. Now, I was fortunate that I receiveda rich person's education even though I didn't grow up rich. And it’s because I’m an only child. And my mother, who was a single mother, spent all of her resourceson my education. And this allowed me to cometo college to the US and eventually get a PhDin computer science. Now because of all of this about 10 years ago, I decided I wanted to do something that would give equal accessto education to everyone. Oh, by the way, this is what I wantto talk to you about today, giving equal accessto education to everyone. At the time, I was a professorof computer science at Carnegie Mellon University, and I decided to work on thiswith my PhD student, Severin. The way my brain works, all of education is justtoo general of a problem. So I decided, let's startby teaching one thing. And then I started thinking,OK, well, what should we teach first? Should we teach math? I mean, we both love math. Me and my cofounder, we both love math. And, you know, we didn'tdecide to do math. Then we started thinking, well, maybewe should teach computer science. But eventually, and this is maybesurprising to people in North America, eventually, we decidedthat the best subject to start with was teaching foreign languages. And let me tell you why. There's a number of reasons. One of them is that there'sa huge audience for it. There’s about two billion peoplein the world learning a foreign language, both in school and outside of schools. Most of these people, by the way,are learning English. About 80 percent of themare learning English. In this weird map right here, all the countries in green are countries in which peopleare predominantly learning English. And the reason for that is because English can trulytransform your life. In most countries in the world, knowledge of English can significantlyincrease your income potential. So this is another reason why we decidedto start with foreign languages. And it's because you can directlymake more money if you learn another language,in particular English. And see, this is pretty differentthan many other subjects. For example, take math. In the case of math, just knowledge of math does notincrease your income potential because usually you have to learn mathto then learn physics to then become a civil engineer,that's how you make more money. Whereas with languages,if you are a waiter and you learn English, now you can be a waiter at a hoteland make more money. So we decided, well, let's get startedby teaching languages. Now, we also convinced ourselves that the only wayto really reach a lot of people was by using a mobile phone,or a smartphone in particular. See, building schools all over the worldis simply too expensive. On the other hand, most of the world's populationalready has access to a smartphone, and the trend is that that fractionis only going to increase. So we decided at the time that we would make a way to learnforeign languages on a mobile phone that was accessible to everyone. And then we called it Duolingo. Thank you. (Applause) Now in order to truly be accessibleto everyone, rich and poor, Duolingo uses a freemium modelto support itself. What that means is that you can learnas much as you want without ever having to pay. But if you don't pay, you may have to see an adat the end of a lesson. Now, if you don't like ads, you can also pay to subscribeto turn off the ads. And it turns out that the vast majorityof the revenue for Duolingo comes from people who payto subscribe to turn off the ads. Now, who are these people who payto subscribe to turn off the ads? Well, they're usually well-off peoplein rich countries like the US and Canada. Who are the peoplewho don't pay to subscribe? They usually come from poorer countrieslike Brazil or Vietnam or Guatemala. So what I like about this model is that it is a small formof wealth redistribution because we're basicallygetting the rich people to pay for the education of everyone. So I like that. (Applause) So with smartphones,we can reach a lot of people and we can even get the rich peopleto pay for the whole thing, which is great. However, if you're trying to delivereducation with a smartphone, you run into a humongous problem. And it is that smartphones come equipped with some of the most addictive drugsthat humanity has ever engineered. TikTok, Instagram, mobile games. See, delivering educationover a smartphone is like hoping that peoplewill eat their broccoli, but right next to it, you putthe most delicious dessert ever made. (Laughter) If you really want to delivereducation to everyone, not only do you haveto make it accessible, but also you have to make itso that people want to actually learn. And with Duolingo,we've been able to do this. And at the highest level,the way we've done this is by making the broccolitaste like dessert. I'll say it another way. What we've done is that we've usedthe same psychological techniques that apps like Instagram,TikTok or mobile games use to keep people engaged, but in this case, we use themto keep people engaged but with education. Let me give you some examplesof these techniques. One of the most powerful onesis the notion of a streak. What a streak is, is it’s just a counter that measures the number of days that you've usedthe product consecutively. You just take that number, you put it very prominentlyin your product and then people come back every day. And the reason people come backevery day is because, well, if they don't come back,that number resets to zero and people don't wantto lose their streak. It works. Now, on the one side, streaks have been criticizedfor, for example, getting teens addicted to Snapchat. But in the case of an educational app, streaks get people to come backto study every day. Now, to give you an ideaof the power of streaks, in the case of Duolingo, we have over three million daily active users that have a streak longer than 365. (Applause) That means they haven't missed a dayin the last year or longer. Now, fun fact about streaks. What country do you thinkhas the longest average streaks for an educational app? It's Japan. Of course. Shortest-ever streaks? Latin America, baby. (Laughter) But we're fun, hey, we're fun. (Laughter) Another important mechanism to get peopleto come back to your product are notifications. On the one side, notificationscan be really spammy and annoying, but in the case of an educational product, people actually wantto be reminded to learn. In the case of Duolingo, we havea very sophisticated AI system that basically chooseswhen to send the notification and also what to say in each notification to maximize the probabilitythat people come back. Now, interestingly, even after all this sophistication, it turns out that the algorithmfor choosing what time to send you a notificationis pretty simple. Do you know what is the best timeto send people a notification? I'll tell you. It's 24 hours afterthey used the product last. There's an easy explanation. If you were free yesterday at 3pm, you’re probably free todayat 3pm as well. So this is what a very sophisticatedmillions of dollars of AI found. (Laughter) It's funny. Now with notificationsyou shouldn't be spamming. And we're not spamming, with Duolingo, we actually stop sending notificationsafter seven days of inactivity. So if you don't use Duolingofor seven days, we stop sending you notifications. Now, at some point it occurred to us, if we're stoppingto send people notifications, we should let them know. So we started sendingthis notification to people saying, \"Hey, these remindersdon't seem to be working. We'll stop sending them for now.\" You know what people dowhen they get this notification? They come back. (Laughter) Passive aggressive. (Laughter) Works for my mother, works for Duolingo. (Laughter and applause) These passive aggressive notifications are really good at gettingpeople to come back back because they feel like our greenowl mascot has given up on them, so they come back. And speaking of ourgreen owl mascot, by the way, because all our notifications comefrom our green owl mascot and well, he's passive aggressiveand also pretty pushy, this has given rise to a lotof memes on the internet that make fun of the great lengthsthat he will go through to get you back to learn a language. Here's one of my favorite ones. This is it's a meme,it’s one of my favorite ones. (Laughter) Basically looks like you forgotyour Spanish lessons. And then there's an intruder alert, presumably the owl broke into your houseto get you to learn language. Now, Duolingo has entered the zeitgeist. And there's thousands of memes,there's SNL skits about it. And it's because we've managedto get people to want to learn a language by using the same techniques that mobile games and social media useto get people engaged. And this is a really important point, let me say this. I don't actually believe that there'sa way to make an educational app be as engaging as something like TikTokor Instagram or mobile games. But the good news is that -- And by the way, the reasonI don't believe that is because ultimately you haveto teach people something. And it's hard to compete with,like, cats and celebrities. But the good news isthat I don't think you have to. See, here's the thing. When you're learning something,you get meaning out of it. Whereas when you're scrollingfor two hours on Instagram, a lot of times afterwards, you feellike you just wasted your time. So I think it's actually OKif your educational product is only 80 or 90 percent as engagingas something like TikTok, because the other 10 or 20 percent will be providedby people's internal motivation, though of course, not much more than that. This is really a key point. If we want to get peopleto do something meaningful, you can use the same techniquesthat apps like social media use to get people to do it. And even if you're not as engagingas those apps are, you can still get hundreds of millionsof people to use your product. In the case of Duolingo, for example, there are more people learning languageson Duolingo in the United States than there are people learning languagesacross all US high schools combined. (Applause) And this is truein most countries in the world. My hope is that -- I knowwe can do this, but, you know, my hope is that as humanity, we can do what Duolingo has donefor learning languages but for all other subjects. Where we can get peopleto learn math with mobile phones, like millions of people to learnmath with mobile phones or physics or whatever. I hope for a future in whichscreen time is not a bad thing, in which we can deliver high-qualityeducation to everyone, rich or poor, using a mobile phone. But the single most important thingthat I can end this talk with, is a reminder to please,pretty please, I beg you, do your language lessons today. Thank you very much. (Laughter) Thank you. (Applause) Helen Walters: Luis, thank you so much. I wonder if you can just saya little bit more about that last point, how do you think you can applythis type of thinking to other subjects? So you mentioned math,and things like that. How do you do that? Luis von Ahn: I think in particular, subjects that are learnedthrough repetition and it turns out most thingsthat are kind of really meaningful are learned throughthousands of repetitions. You learn to read through repetition, you learn elementary school maththrough repetition. Most things that you can learnthrough repetition, you can actually gamifyand turn into something like Duolingo, where people justdo it a lot and do it fun. It's a little harder for thingslike explanations. That probably is going to requiresome really good videos. Sal Khan is doing a reallygood job with that. But for things that requirea lot of repetition, I think we can use the same methods. (Applause)