Behind the product: Duolingo streaks | Jackson Shuttleworth (Group PM, Retention Team)

Jackson Shuttleworth is a Group PM at Duolingo, where he leads the retention team and the powerful streak feature. The streak feature, which gamifies consecutive days of learning, has been Duolingo’s most important and innovative growth lever and a key driver of their growth to a $14 billion business with almost 600 million users. In our conversation, we dive deep into the history and lessons of this feature: • The evolution of the streak feature • Biggest insights from over 600 streak-related experiments • Biggest specific wins and misses along the way • Key principles for building effective streak mechanics • How to operate a high-velocity product team • Tips for building engaging notification systems • Much more — Brought to you by: • Pendo—The only all-in-one product experience platform for any type of application: https://www.pendo.io/lenny • Vanta—Automate compliance. Simplify security: https://vanta.com/lenny • Coda—The all-in-one collaborative workspace: https://coda.io/lenny Find the transcript at: https://www.lennysnewsletter.com/p/behind-the-product-duolingo-streaks Where to find Jackson Shuttleworth: • LinkedIn: https://www.linkedin.com/in/jackson-shuttleworth/ In this episode, we cover: (00:00) Jackson’s background and an overview of Duolingo’s streak feature (06:00) The impact of streaks on Duolingo’s success (09:58) The origin and evolution of streaks (14:50) Key experiments and insights (24:38) User psychology and engagement strategies (28:36) Duolingo’s product review structure (33:07) Designing for clarity and adaptability (46:59) Developing the Streak Freeze feature (50:47) Balancing monetization and retention (54:08) Notification strategies (58:15) The Perfect Streak feature (01:00:40) Enhancing the user experience (01:04:47) Team operations and experimentation (01:18:57) Who can benefit from streaks (01:21:00) Lightning round Referenced: • Duolingo streaks: https://duolingo.fandom.com/wiki/Streak • How to make learning as addictive as social media: https://www.ted.com/talks/luis_von_ahn_how_to_make_learning_as_addictive_as_social_media?subtitle=en • Luis von Ahn on LinkedIn: https://www.linkedin.com/in/luis-von-ahn-duolingo/ • FarmVille: https://en.wikipedia.org/wiki/FarmVille • Royal Match: https://www.dreamgames.com/games/royal-match • How Duolingo reignited user growth: https://www.lennysnewsletter.com/p/how-duolingo-reignited-user-growth • You’re on fire! Or, how we brought the streak milestone to life: https://blog.duolingo.com/streak-milestone-design-animation/ • Duolingo Doubles Down on Design and Animation with Acquisition of Hobbes: https://investors.duolingo.com/news-releases/news-release-details/duolingo-doubles-down-design-and-animation-acquisition-hobbes • Hobbes: https://www.hobbes.work/ • Jira: https://www.atlassian.com/software/jira • Atlassian: https://www.atlassian.com/ • Bing Gordon on LinkedIn: https://www.linkedin.com/in/binggordon/ • Peloton: https://www.onepeloton.com/ • Bluey on Disney+: https://www.disneyplus.com/series/bluey/1xy9TAOQ0M3r • Emily in Paris on Netflix: https://www.netflix.com/title/81037371 • Multi-position ladders at Home Depot: https://www.homedepot.com/b/Building-Materials-Ladders-Multi-Position-Ladders/N-5yc1vZasew Recommended books: • A Guide to Midwestern Conversation: https://www.amazon.com/Guide-Midwestern-Conversation-Taylor-Phillips/dp/1984861336 • Fate Is the Hunter: A Pilot’s Memoir: https://www.amazon.com/Fate-Hunter-Ernest-K-Gann/dp/0671636030 Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email [email protected]. Lenny may be an investor in the companies discussed.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Lenny Rachitsky?

  Duolingo is a $14 billion company that's hitting all time highs too. It just keeps going up. I think it doubled in value in the past six months. Streaks is the most impactful feature.

• 0:08Speaker 01

  We have right now over nine million users with a year plus streak. If you look at the numbers, I think it's been our biggest growth lever. What Duolingo really focuses on is, you know, how do we help users build habits around language learning? Getting user come back the next day is the biggest problem to solve.

• 0:24Lenny Rachitsky?

  Let's get into the mother load of learnings from the journey of streaks. Talk about the key lessons, insights, and also wrong turns along the way.

• 0:30Speaker 01

  I'd say like, test everything. We've run in the last four years, over 600 experiments on the streak. So every other day, we've actually set up really good infrastructure for copy testing. We used to say continue, our like standard CTAs continue. And we changed that to commit to my goal and it was like a massive win.

• 0:48Lenny Rachitsky?

  There's so much human psychology that you all learn through all these experiments of just like how to motivate people. What motivates, what demotivates.

• 0:54Speaker 01

  Say that you played a mobile game, that you've done it for 3,000 days in a row. I don't know, maybe that hits a little bit different than you've learned Spanish for 3,000 days in a row.

• 1:07Lenny Rachitsky?

  Today, my guest is Jackson Shuttleworth. Jackson is a group product manager at Duolingo, leading the retention team. This is a different kind of episode that I'm experimenting with, where we spent the entire conversation focused on the journey and lessons of a single feature. In this case, Duolingo Streaks. Duolingo is a $14 billion business. Just over the past six months, they doubled in value. They're hitting all time highs in usage and market cap. They're also one of the very few successful and also the single biggest consumer app business in the world. And as you'll hear from Jackson, the streaks feature is the single most impactful feature that most contributed to this growth and success.

• 1:50Lenny Rachitsky?

  In other words, you could argue this one feature created billions of dollars of value, which to me means it is worth studying in depth. In our conversation, Jackson shares the history of the streaks feature, all the biggest wins and wrong turns they've taken along the way, what he and his team have learned about what works and doesn't work with a streaks mechanic, and also how they set up their teams to operate in a way that allows them to run over 600 experiments on this product and continue to find big wins. I hope to do more episodes like this on features and products that you'd love to hear more about. So leave a comment either on YouTube or on Substack and tell me which product or feature you'd love to see me cover. And if you enjoy this podcast, don't forget to subscribe and follow it in your favorite podcasting app or YouTube.

• 2:33Lenny Rachitsky?

  It's the best way to avoid missing future episodes and it helps the podcast tremendously. With that, I bring you Jackson Shuttleworth.

• 2:44Lenny Rachitsky?

  Jackson, thank you so much for being here and welcome to the podcast.

• 2:48Speaker 01

  Yeah, thank you. Longtime listener, first time caller, so.

• 2:51Lenny Rachitsky?

  I appreciate it. So this is going to be a really interesting conversation. I've never done an episode like this before where we basically spent like an hour, an hour and a half going into one feature of one product. But this is a very special feature. It's a very special product. Have you ever spent like an hour, an hour and a half just talking about those one feature with anyone?

• 3:13Speaker 01

  Well, internally, so when we onboard new folks to the team, we'll do, I actually just did this with somebody that joined the team recently where we spent, and I was like, hey, let's spend an hour just talking about the streak. We got through an hour and I got through about 30% of what I wanted to share. There's just so much, we'll talk about this, but there's so much that we've learned over the years, but never anything externally like this. I think we've shared bits and pieces of learnings, but this will be like the motherload of learnings, hopefully, of how Duolingo's built the streak.

• 3:42Lenny Rachitsky?

  We should title this, "The Motherload of Learnings of Duolingo Streaks." This episode is brought to you by Pendo, the only all-in-one product experience platform for any type of application. Tired of bouncing around multiple tools to uncover what's really happening inside your product? With all the tools you need in one simple to use platform, Pendo makes it easy to answer critical questions about how users are engaging with your product and then turn those insights into action, all so you can get your users to do what you actually want them to do. First, Pendo is built around product analytics, seeing what your users are actually doing in your apps so that you can optimize their experience. Next, Pendo lets you deploy in-app guides that lead users through the actions that matter most.

• 4:26Lenny Rachitsky?

  Then, Pendo integrates user feedback so that you can capture and analyze what people actually want. And the new thing in Pendo? Session replays, a very cool way to visualize user sessions. I am not surprised at all that over 10,000 companies use it today. Visit pendo.io/leni to create your free Pendo account today and start building better experiences across every corner of your product. P.S. You want to take your product-led know-how a step further? Check out Pendo's lineup of free certification courses led by top product experts and designed to help you grow and advance in your career. Learn more and experience the power of the Pendo platform today at pendo.io/leni.

• 5:09Lenny Rachitsky?

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• 5:52Lenny Rachitsky?

  Get $1,000 off Vanta when you go to vanta.com/leni. That's V-A-N-T-A dot com slash leni. Okay, so for people that don't know anything about what Duolingo Streaks are, can you just first give a brief explanation of what is Duolingo Streaks? What is this feature all about?

• 6:10Speaker 01

  Well, presumably people know Duolingo is a language learning app. The Duolingo streak tracks currently, anyway, how many days in a row you've done a lesson. So you come to Duolingo, you do a lesson. Your first lesson, you'll start a streak and then every consecutive day that you come, use the app, you'll extend your streak. And I should actually put an asterisk around how many days in a row, because we also have built flexibility into the feature. So we have these things called streak freezes. It's like insurance for your streak. So it's a pretty simple feature in theory, but over time, we've layered on challenges and goal setting and rewards and social features. A lot of our notifications are tied to the streak. So pretty simple feature to understand,

• 6:55Speaker 01

  but it's been a really rich feature for us to build on top of.

• 6:58Lenny Rachitsky?

  Some people might be hearing this, be like, whoo, Duolingo streaks? So like, what's the big deal? There's other people that are like, holy shit, I want to learn everything I can possibly learn about Duolingo streaks. So many companies are trying to copy what you've learned from this. Give people a sense of the impact that this one feature has had on Duolingo's success and growth.

• 7:14Speaker 01

  This is, and this is not just the subjective retention PM talking. I think this is our biggest feature, with the exception of the lessons. And I think it's actually where to start that. Like streaks are a great engagement hack. I'm kind of of the opinion that any team, any app out there can introduce a streak. And if you figure it out, it probably works to retain users. But at the core, you have to have an app that people want to use. And people really like using Duolingo. It's fun, it's delightful, you learn something. And so it allows us to layer an engagement mechanic on top of that. Like the streak is really powerful. So it ships a disgusting amount of DAUs. Again, it is just, it is our, one of our golden geese. And again, what's cool is that like, you look at notifications.

• 7:57Speaker 01

  Notifications for Duolingo is massive. I mean, us sending better, whether it's copy or timing. So many of our notifications work because they reference the streak, because users care about the streak. And so not only is it itself, us iterating on the streak, a huge driver of DAUs, but it's also something that enables other really high valuable features. I was looking up some stats before I came on and it's pretty crazy. So we have right now over nine million users with a year plus streak. So nine million of our users have had. Uh, use Duolingo every or almost every day for, uh, you know, well over a year.

• 8:40Speaker 01

  Um, which, which is pretty, which is it's, I don't know. It's, I like to imagine things in terms of like, you know, okay, well, like if you put all these people in a city or, you know, in a place, where would it be? And like, ah, it's like a very large city, nine million people. So.

• 8:53Lenny Rachitsky?

  For a year have been, have a year long streak. That's incredible. I was just looking at the, the stock of Duolingo. So Duolingo is a $14 billion company at the time of recording this. It's hitting all time highs too. It's like, just keeps going up. I think it doubled in value in the past six months, something like that. And what I'm hearing from you is streaks is this, other than just like the core learning feature, which is just like the product of Duolingo, this is the most impactful feature in terms of growth and in that retention specifically.

• 9:23Speaker 01

  I mean, if you look at the numbers, I think pretty objectively has been our biggest growth lever for, for driving DAUs. And also say a lot of it's just related to how we think about growth at Duolingo. And a lot of what we try to do is organic growth. You know, we think about growth, you know, just as much as bringing new users onto the platform is not losing them. If you're just bringing people onto the platform and then they churn, that's not going to be sustainable. And so as much as we can do to keep our users coming back and actually retaining as users, it's going to make it, it's going to give us a much easier base to continue growing DAUs off of.

• 9:57Lenny Rachitsky?

  Perfect. Okay. Talk about how this feature originally came to be. What was the original version of it? Was the original insight that led to be one?

• 10:04Speaker 01

  Yeah. So the oldest streaks are as old as Duolingo itself. We, when we launched Duolingo, we, we launched with a streak. And I say we, I was like just graduating undergrad when, when Duolingo launched. Uh, so this is well before my time. Uh, but we launched with a streak feature. The, you know, the initially how, how the, how the feature worked was you'd come to Duolingo and you'd set a goal for yourself. Um, and it was an XP based goal. So Duolingo, a little bit of like, you know, nomenclature, we have a experience point in space system that drives a lot of our features in the app. And the way you'd said it is you'd say, you know, based on what your language learning goal was, you know, maybe you have a 10 experience point goal versus a 50 experience point goal. And so extending your streak would be, hey, can you hit 50 experience

• 10:49Speaker 01

  points if that's what you set your goal to be? And this worked well. I think this also speaks to like how Duolingo initially grew. You know, we were, Luis launched it with a TED Talk. You know, we probably had a more tech-forward user base, you know, initially. And so this whole idea of like an experience point-based streak system made sense. But what that also meant is that you could have a user come and use the app, do multiple lessons a day, and maybe they just set too hard of a goal for themselves and then lose their streak, which I don't, you know, you don't need to be an expert in streaks to understand. That's, that's probably not good. You know, the nice thing with how we initially set it up, though, is it really did connect with what your goal was. So if you were serious, let's track how good you are at being a serious language learner. But I'd say one of the most impactful experiments we ran was about, this was actually as I

• 11:33Speaker 01

  was joining, we, or just after I joined, we had, we had run this experiment, was to move it from a XP-based streak to just do one lesson a day and you'd extend your streak. And, you know, the risk that you can sort of imagine is, well, then users kind of care less about it because it's not connected with their goal. And we saw none of that. I mean, this was huge driver of DAUs, just making it, making it easier to extend your streak. But I think really importantly, is still meaningful, right? Like, the unit of use, and, you know, as you're thinking about building a streak, like, I think it's really important to think about, like, what the unit of use of your app is. The unit of use for Duolingo is like doing a lesson. And so if what we care about is users coming back every day and doing a lesson because it shows that they're actually engaging with

• 12:16Speaker 01

  the app, then it doesn't hurt us to make our streak focus on just do one unit versus multiple. And so that was like, probably the big sea change experiment that we ran, you know, at the time was moving from an XP-based streak to a one lesson streak. It's also simple. And I think that's like, one of the things to think about with streaks. It's always easy as a PM to like, Have a million goals or objectives for what you want your feature to be and potentially build a more complex feature. You know, one lesson streak, it's just easy for more users to understand.

• 12:45Lenny Rachitsky?

  Yeah, that's exactly what I was gonna say. And just for folks that aren't super familiar with XP, it's basically experience points and you get them from like doing things.

• 12:52Speaker 01

  Yeah, you do. You do stuff on Duolingo and then based on what you did and how well you did it, we give you experience points. This actually drives a number of our features in our app. So leaderboards is the big one. You know, we have a leaderboard system where you try over the course of the week, you battle with 29 other people and you want to win. That's all driven by XP. So we do have other features in the app that really benefit from this XP system. The streak is just no longer one of them.

• 13:18Lenny Rachitsky?

  Awesome. Okay, so I want to talk about the journey from that point to what it is today, but a quick tangent. I saw Luis tweet just this week, someone asked him, how do you decide whether to optimize for learning or engagement? And he's like, no question. Everything we do is focused on engagement because you won't learn anything if you're not coming back to the app.

• 13:39Speaker 01

  As an engagement PM, that was like the coolest thing he could have ever said. It's, well, again, very much as a, you know, subjectively, I guess, as an engagement PM. I mean, that's how I've, you know, I, I'm sure my learning, the, the learning folks at Duolingo will cringe when they hear it. Like, I see myself as a learning PM as much as an engagement PM because the easiest way not to learn on Duolingo is not to come back the next day. And so if we don't make the app retentive, you will have no opportunity to engage with our learning features. Now, I do think that there is a long tail of learning where if you start to dumb down, and honestly, this is, this is something we wrestle with the streak as well, you start to dumb down the experience and your users aren't actually learning, they're not going to care. I mean, streaks work best when they're sitting on top of an app, you know, that, that users

• 14:24Speaker 01

  care about. But yeah, I mean, if, if you can't come, you know, if you don't come learn on Duolingo, you know, if you don't come back to Duolingo, then you're not learning. So, um, no, we, I mean, we track a lot of this with, you know, the work that we do, we make sure that as we're making changes to the streak, we're not hurting the learning experience and we don't have a ton of interaction with it. So we're constantly thinking about this, but thank you, Luis, for saying that.

• 14:48Lenny Rachitsky?

  It makes sense to me. Okay, so let's get into the mother load of learnings from the journey of streaks. So the first version went from XP to one lesson. Talk about the... Key lessons, insights, and also wrong turns along the way to what we see today.

• 15:02Speaker 01

  Duolingo has very much, you know, has a, has a strong like test it philosophy. You know, we're willing to test a lot of different, honestly, we'd much rather test it than like debate it for, you know, days and days. So we actually followed up this experiment with, and this is, this is a little bit later with, hey, what if we make it even easier to extend your streak? And so we actually tested, hey, if you, if you do one exercise, just one exercise in a lesson, we'll, we'll extend your streak. And, and a lot of like, the insight was good. Like you look at the funnel, hey, there's a lot of users who are starting, but not finishing lessons. They're not extending your streak. The loss aversion doesn't kick in. They don't, you know, come back.

• 15:42Speaker 01

  So this kind of followed that train of thought. What we realized when we ran this experiment is, um, you know, DA used moved not one bit. And, and what we, what we were doing by, and this, if we go back to like unit of measure, you know, we had, we had dumbed down the unit of, and nobody thinks about, I just want to come. You do one question on Duolingo. Nobody thinks about that. Um, so we had more like a, a less clear unit of measure that we were basing our streak around. And, and the users that we are capturing with our streak, you know, you come, you do one or two questions on Duolingo, then you leave. We're like the least engaged users imaginable. And so, you know, I think that's something also to think about as you're building your streak is like, what is the user that you're solving for?

• 16:24Speaker 01

  So not only what is the kind of habit that you're building for, but like, what is the level of commitment? And that was an example where we over indexed on a type of user who we honestly just weren't going to keep. That was a very easy shutdown, uh, shutdown decision.

• 16:39Lenny Rachitsky?

  That's an awesome story. I just, just to comment on that real quick, just like you went like, let's just go to the extreme and make it just like streaks. Yeah. Get everyone going streaks forever. And then I love that it turned out and as it's not bringing users that you want. And it's dumbing down experience. It makes me think of Farmville where you have to go and like harvest your crops every whatever hour. And just like, like that lasts for a bit. And then eventually people are like, what the hell am I doing with my life?

• 17:03Speaker 01

  Exactly. No, we, I mean, and we test every, so we, I was looking at the numbers as well. We, we've run in the last four years, over 600 experiments on the street. So every other day effectively. We're running an experiment and they range from big like this, like changing how the mechanic works to like, let's swap a string with another string and see if that copy is better, you know, for, for users. So, so we're constantly testing on, on everything. I do think that like, I'd be more careful running that experiment now. Like at some point, your streak gets big enough that, again, I got nine million users on the streak. I gotta be really careful. Those are our best retaining users. You know, you gotta be careful. But in the early days of the streak,

• 17:43Speaker 01

  I'd say like, test everything. I mean, see what, don't get, don't get super caught up and it has to be like this. Just test a bunch of stuff and see what speaks most to users. Cause I think, you know, again, you will constantly be surprised by the, the insights that you get from whether you, we, we shut down about half of our experiments. So, half of our, of our experiments lose. We still learn a ton by virtue of, of running them. So, super, super valuable.

• 18:08Lenny Rachitsky?

  That's actually a good success rate. A lot of companies have only 20% experiments be positive. What's your policy on it? If it's neutral, do you ship it or do you kill it?

• 18:18Speaker 01

  It really depends. If, if we're adding something and it's, and it's neutral, we tend to, to shut it down because it's just more cognitive load. It's something that we're gonna have to start building around, a new UI element that we have to figure out how it fits into our system. I'd say when we do ship a neutral experiment is something that, that we have real conviction around, okay, yeah, maybe this was neutral, but it's gonna give us a new platform to then build on top of. So, that experience might be neutral, but now we can build these DAU positive experiments. And my general take there is though, in that case, build that in as part of your V1 so that, you know, you make sure that like, at least your hypothesis around this

• 18:59Speaker 01

  roadmap, you know, has play, you know, should probably be the case. But in general, shutting down a neutral experiment so you don't introduce more complexity to the app is, is, is the way we tend to go.

• 19:10Lenny Rachitsky?

  Makes sense. All right. What else? What else have you learned along the journey?

• 19:13Speaker 01

  Well, I mean, maybe I can talk about a few different ways that we structure, you know, a few different themes that I think we, we, we lean on. So, the first is, Focusing on the zero to seven day user experience. And I would say this is, if you look at the kind of, you know, whatever breakdown of experiments are, we run definitely more than average number of experiments on getting users to go from a zero to seven day streak. And a lot of this is because we've looked at the data for, you know, our retention curves. And what we found is that once you get to seven days, loss aversion kicks in and you retain. So going from a one to a two day streak, huge jump in retention. Two to three day streak, slightly less, but still huge. And it's up until day seven. Once you hit day seven, it flattens out.

• 19:56Speaker 01

  And it's not to say that like, you know, if you're a, you have a 30 day streak, you're way more attentive than day seven, but not in the order of magnitude that it is from, from day one through seven. So we do a ton of work to get users to that point where loss aversion kicks in. And then they don't want to, they don't want to leave the app. One of the fun ones that we did, and it's honestly as much about process as it is about the feature itself was, we have a feature called streak goal. And it is, again, so much of this stuff seems so obvious in retrospect, but you know, it was really novel at the time. You know, we, we had this idea of like, hey, maybe we'll just goal users to hitting a certain streak length. As you can imagine, this is pretty powerful, you know, user psychology.

• 20:40Speaker 01

  And we started with the simplest version of this. And this is how Duolingo does a lot of our testing, you know, rather than design the big, complex feature for V1, just do like the simplest encapsulation of what that feature can be, see if it has legs, and then just add to it iteratively over time. This is partially how we get to, you know, 600 plus experiments on streaks. They're not all big ones. But we started, and it was funny, we actually took a learning from our monetization teams. And one of the strings that they had, the pieces of copy that they had worked really, really well was, I think it was you're like 5.6 times more likely to finish the course if you subscribe to plus. And so, you know, now it's super our subscription. And it was, it was a really good hook that if you, if you really cared, you'd sign up.

• 21:24Speaker 01

  And so we ran a similar, we, we had a similar thought where it's like, oh, let's just tell you how much more likely you are to finish the course if you get a 30 day streak. And so we started with that, and I think it was like, you're seven times more likely to finish the course if you have a 30 day streak. And just that message, when you started your streak, us telling you that was awesome. Huge win.

• 21:46Speaker 01

  You know, indicating an outcome and like Duolingo doesn't have, we don't, but we have a gem economy, but we don't actually have like, you know, it's just, it's all you learning. But being able to actually talk about it in terms of the outcomes that a user would think about. In this case, trying to finish the course was a huge win. So this is where we started and we're like, ah, goal setting. All right, we, we should go much harder on that.

• 22:06Lenny Rachitsky?

  Found some.

• 22:08Speaker 01

  Thing and now let's just beat the heck out of it. So we followed that up with another experiment where we, we tested different lengths. So we'll test 14 days and in 50 days. We found that they were all good, but they, they appealed to different users. And so we started to realize, all right, well, we probably need to be more thoughtful about who we give, you know, these different options to. And, and, and so then we followed that experiment up with, all right, let's start with 30 days. And then we're going to let you opt out. You know, we'll, we'll say, no, I don't think I can hit it. And our thinking was, and then if you say no, we'll hit you with an easier goal. Cause we just wanted to get you to commit to a goal. And this was a fascinating one because it was a good win to give users that easier goal, to try to capture, capture them before they said no.

• 22:54Speaker 01

  But it was almost just as big a win to add that opt out button. So we tested separately and I'm a huge fan of testing like way too many arms for an experiment, just to like be able to isolate your hypotheses. But, but we captured, you know, just what happens if we add an opt out button? And adding an opt out button, when you would think like as a PM, oh, I'm like, you know, now users might not engage with my feature. That's a bad thing, but it was a huge win to let them do that. And, and the learning here was that this intentionality of saying, no, I want it. Previously it was just a continue button, but now it's like, no, I want to hit 30 days. And, and, and having that be an intentional decision for them, yes or no? Even though again, this had no impact, none of, or no impact past this screen.

• 23:36Speaker 01

  Everything that I'm talking about now was, uh, you know, just that screen that day. And then was all thrown out. So that optionality was, was, was, you know, a huge insight. And so because of that, we built a, a goal setting feature where you could choose between different goals, giving users that optionality was, was likewise a huge win. I'll say one, one final learning on this. Again, you talk about like friction and, and good and bad friction. We thought, once we built, you know, a goal picker screen where you could pick between different streak lengths, we, we were like, oh, well, let's like recommend that users do a hard, you know, a harder goal. Thinking that, okay, well, a harder goal is going to be better retention and, and we'll pre-select the harder goal for them.

• 24:20Speaker 01

  And this, based on all the learnings that I just shared with you, you probably imagine, lost pretty significantly. We realized that like, yes, we could speed users through the screen more by virtue of picking a goal for them. But like, that act of selecting, I think it's 30 days, I think it's 14 days, was where we were getting so much of the engagement from this feature.

• 24:39Lenny Rachitsky?

  There's so much human psychology that you all learn through all these experiments of just like how to motivate people, what motivates, what demotivates. It was like, you guys should write a book on human psychology and motivation.

• 24:51Speaker 01

  I, I feel very much like a amateur armchair psychologist with everything that, at least as far as people who want to learn languages on their phone go.

• 25:01Lenny Rachitsky?

  Right, right.

• 25:01Speaker 01

  Like, I really understand those folks.

• 25:03Lenny Rachitsky?

  So one, one kind of theme I'm hearing here so far is you guys are basically just like mining for gold, just like looking for like a vein in some mine. And once you hit it, you're like, ooh, this worked. You just go crazy on just testing all kinds of things to see if you, how far you can take that one little light thread.

• 25:22Speaker 01

  Yeah. And I think, you know, I, I, I shared that, that the, how this idea came partially from, you know, monetization win that they had. I think there's a lot of, you know, because Duolingo runs, you know, I don't know what percentile we're in, but it's got to be a very high percentile of, you know, per capita experiments run for a company. You know, based on company size, we're just constantly learning so many things. And there's a really great cross sharing of. Modernization say, hey, this thing worked for us. Is that something you can use? So I'd say it's rare that we go into something where it's just like, well, let's just, let's just try something. Typically, we have some insight because of all of these experiments that we've run that, hey, if we do this, I don't know, it's one here or it's worked here, it's driven this user engagement.

• 26:07Speaker 01

  If we, you know, sort of massage that and make it, you know, try it in this, um, you know, scenario or like a different screen. You know, we, we come in at least with a strong hypothesis that this will work. A lot of times we do look and we're like, you know, a lot of the apps that we look at actually are games themselves. So it's like, all right, you're playing Royal Match or, you know, there's the new Pokemon, uh, trading card game that I'm spending way too much time on. You know, you, you, you look at these games and see what they're doing and it's really good fodder for what we can do. But a lot of times you're at least going with a strong hypothesis based on what you've seen work elsewhere.

• 26:39Lenny Rachitsky?

  Got it. So just to double down on that point, it's not like just random experiments. It's here's a hypothesis, we're fairly confident or has a chance to be true. Let's try it. It's not just, yeah, just try everything.

• 26:49Speaker 01

  And I think that like, how strongly you feel about the hypothesis directly ties to how hard that experiment is. Like with copy, for instance, we, we've actually set up really good infrastructure for copy testing. And I'm of the opinion that companies should run, as long as you have the user base to do it, like copy test constantly. Like the amount of copy tests that we've had that is just like, that have won and you, I don't know, you just, you just try things and you figure out what wins is, is definitely legion. And, and if ship like massive wins from little copy changes.

• 27:18Lenny Rachitsky?

  Is there an example of that, of just like the impact?

• 27:20Speaker 01

  Going back to that goal screen, um, we used to say continue are like standard CTAs continue. And we changed that to commit to my goal. And it was like a massive win, even just, you know, and again, it was like, okay, users tapping on that. What are we asking them to do? Commit to the goal. What is that going to lead them to do? Commit, not, you know, churn. Just that little copy change, that one time right there led to, to huge wins. And in copy changes are so cheap, like it's just, you translate us, you know, for us, you know, we, we have a lot of, uh, you know, users all over the world and a lot of UI languages. So, but like just come up with a bunch of ideas, translate some strings. This is one where, you know, the, the feedback that you'll typically get from Luis. So all of our changes at Duolingo go through product review that, you know, are reviewed by Luis.

• 28:05Speaker 01

  So Luis reviews every single change that, you know, we, we propose or every experiment that we run. To believe copy, he's just like, I don't know, test it. Like, there's, there's nothing better than be told by Luis, I don't think this is gonna win, but sure, if you want to. And a lot of times, you know, to his credit, he's right. And a lot of times, you know, our intuition was right, but it's just so cheap to do it. I think when the lift is smaller, it's great to have hypothesis, but you know, you don't need to beat it up too much.

• 28:36Lenny Rachitsky?

  So on this thread, I didn't realize Luis reviews everything you're planning to change. And this may be the answer to the question I was gonna ask, which is one of the criticisms of running a product and company this way of just experimenting constantly with all these micro improvements and changes is it can lead to something like a monstrosity of a product and experience that isn't consistent and cohesive and just like, that often happens. Is the solution to that, having the founder basically review all the changes? Is there anything else y'all do to avoid it moving and becoming Farmville or whatever? It's a good example there.

• 29:06Speaker 01

  Yeah, I, our, our product review structure where we've got our head of product design, one of the lead, you know, the, the product management leaders and then Luis and PR. And because they see everything, it, you know, and they have a really high product bar. And so that helps. I think over time, we just as PMs have to look at, okay, where is our feature headed? And so, you know, we do this with the streak, at least on a quarterly basis to look at, okay, well, what, what have we learned? You know, how is our streak developed? And how do we imagine this going in your future? I don't think, you know, it's, it's easy to do, you know, and end in some sort of awful local maxima if you're not constantly looking at your roadmap and think, and you know, you don't have a clear strategy, you know?

• 29:51Speaker 01

  For me, it's like, if you have a clear strategy for where your feature is going, hopefully all of those A B tests are not just done, you know, to get some cheap gain, they're done with a long-term goal in mind. I do think though, and we do this every now and then with the streak, eventually you just hit a local maxima and you say, like you talked about launching neutral experiments. This is a great example where it's like, all right, cool. Now we need to throw a bunch of this stuff out based on all the learnings. Can we reset this real estate? Can we reset this UI, reset this feature in such a way that is just as good as what we have now, but is way more plain or, or simple that we can, again, start to layer on it. Those are hard, those are really hard experiments to, to get win on, you know, to win, obviously, because they are so optimized, but they're really important to do.

• 30:34Speaker 01

  Otherwise, yeah, you just end up with a, a kitchen sink of a feature.

• 30:38Lenny Rachitsky?

  One other tidbit I just want to mention, something that the advantage you all have that other companies don't have is people want to learn, like they want to learn the language. And so getting pushed to come back to an app for something that they want to do is not an advantage a lot of products have. So anything you want to add there of just like, this is why Duolingo might be a little different from what you're working on?

• 31:02Speaker 01

  I mean, that is definitely a benefit. If I had an app that, this is, this is actually why I think a lot of mobile games do streaks differently because, you know, to say that you played a mobile game and as somebody who plays a lot of mobile games, you know, that you've done it for 3,000 days in a row, like, I don't know, maybe that hits a little bit different than you've learned Spanish for 3,000 days in a row. I think the comparison set is much larger, though, than a lot of companies give them credit for, you know, themselves credit for. And I think that there's, I mean, there's a lot of ways that companies think about their, there are very few companies I imagine out there in the world saying, oh, we don't do some degree of good for our users. Even if it's like a game, it's like, I don't know, you're like making your, giving somebody a moment away from the craziness of their

• 31:47Speaker 01

  lives. And so I do think, though, that is contingent on companies who are going to figure out if a streak works for them, to figure out how can you frame the streak in such a way that a user does feel good about it. And it's easier for, you know, a Duolingo, but, you know, I think there's creative ways to phrase this for users. You know, the other thing, maybe just on that, that I'll say is, the streak works really well for Duolingo because with language learning, it's really hard to see day-to-day progress and becoming more fluent. Like, become, and fluency is, is, is not even the right word. It's like becoming better at Spanish or whatever. It is a years-long process for someone to get better at a language. I mean, Duolingo makes it easier, but you still got to put in thousands

• 32:28Speaker 01

  of hours if you're going to reach, you know, C1 or C2 fluency. And, and that is really hard to track on a day-to-day. And so the streak works really well for us because we not, might not be able to tell you, hey, you now know. 0.01% more Spanish, but we can show you, hey, like, you've gotten your streak a little bit higher. And so I think this works particularly well when you're an app that is doing something that's going to be sensed or felt over a longer term to help contextualize that progress in a way that makes more sense, or at least feels more tangible to a user.

• 33:02Lenny Rachitsky?

  Great. That was a great context, empowering to a lot of companies that aren't necessarily doing language learning. Okay, so I took us on a long tangent away from lessons and experiments you ran along the journey of iterating on the streak. So a few things you've shared so far is just like it started being like, it started with this XP idea and then went to like a lesson, then you iterated on ways to make it simpler, maybe harder, you had a streak goals where you commit to like, I'm going to hit a certain goal of streak. What else? What else have you found that has worked, didn't work, lessons learned?

• 33:32Speaker 01

  You know, again, sticking with this one to seven day streak, you know, it is, the idea of a streak, particularly probably to this audience is like, obvious, like, oh, it's a streak, it, you know, goes, it just counts so many days. We've realized over time that a lot of users do not understand how a streak works. And, and it can be as big, you know, as small as, well, I don't understand how streak freezes work, or I don't, like my mom the other day was talking to you about it. She's like, oh, my, I like, didn't use Duolingo and I come back and my, you know, streak's still there. So like, there's like certain elements of the feature that, you know, we can do better at explaining, but even like, what a streak is, it's, it's tracking how many days that I've used the app. Yeah, the

• 34:14Speaker 01

  more that we can make the feature easily comprehensible to users, the more retentive it is. And it, and, and we've run a number of experiments to do this, you know, as simple, you talked about, you asked about early easy copy changes that we made. Actually, this is my first win, experiment win, when I joined Duolingo was, when you start a streak, we use, we have little copy at the bottom of the screen that just, I don't know, it's kind of like flavor copy. We use it to celebrate you or give you context. And I ran some tests that just like tried to in eight words, explain what a streak was. That was it. And it was a massive win because it really required, like it really dumbed down, here is exactly how the streak worked. And it really helped users just understand what they needed to

• 34:58Speaker 01

  do. And I think this is something that's like, you kind of constantly got to remind yourself, particularly if you work in tech and you're building cool tech features, but your user base is not. A bunch of tech workers to like, think about, all right, who is my audience? And for us, it's not just like tech workers, I people in America, people all over the world of all ages, of all cultures. And so making sure that your, your, your feature is even something as simple as the streak is understandable is critical.

• 35:27Lenny Rachitsky?

  What was the actual copy? Do you remember?

• 35:29Speaker 01

  It was, it's still, I think it's still on the app. Like start a day to extend your streak, but miss a day and it resets, something like that.

• 35:38Lenny Rachitsky?

  Makes sense to be very clear.

• 35:40Speaker 01

  Yeah.

• 35:41Lenny Rachitsky?

  Eight words. I love that. Okay. And then when you say massive win, by the way, just to give people a reference point, what do you, what does that look like? What is a massive win in this scale?

• 35:49Speaker 01

  Well, and it's, and it's funny. I mean, this was, and this was four years ago, but I think it was like in the order of magnitude of over 10,000 DAUs for us. And actually, maybe this small bit of context, so Duolingo really cares about the metric, cur, um, current user retention rate. And actually, our first ever Duolingo post with Lenny was the newsletter that our former head of product wrote, Jorge.

• 36:11Lenny Rachitsky?

  The still the single most popular newsletter post of all time in my newsletter across 300.

• 36:15Speaker 01

  I would highly recommend that if you are interested in this, give it a read. You know, to summarize, basically what we found is that if we wanted to drive DAUs and Duolingo cares, you know, our growth North Star is DAUs. The metric that is most effective, you know, where a percentage change in that metric is, is most effective at driving DAUs is current user retention rate. And this is just users who are not newer resurrected, getting them to come back tomorrow. And so most of the work that our teams do, our retention based teams do is focused on cur. And so the retention team that I lead focused on cur, it just so happens the streak is the best feature at driving cur. And so this was, this experiment was the biggest cur win that we had had.

• 37:00Speaker 01

  That was like a top three Kirwin anyway for us. Just this little copy, right? And that's why I say like, that's copy a thousand different ways. Sometimes it's not the big, beautiful feature, you know, that's going to drive the huge gains. Huge gains. Sometimes it's just something as simple as a few words.

• 37:15Lenny Rachitsky?

  I love this. Okay. So when you said 10,000 DAUs, I think that references you guys measure incremental impact and absolute numbers of new daily users you're going to drive with attributed to that experiment. That's what it's.

• 37:28Speaker 01

  Yeah. And we, we do both. I mean, we'll also look at like, a lot of times I'll look at, you know, for retention, day one versus day seven versus day 14. A lot of what I'm looking for is for us to have a better day 14, excuse me, better day 14 impact than better day, day one impact. Cause it means that users are retaining better over time. This is particularly for users that would see a feature multiple times. I just like absolute DAU numbers because as long as you're controlling for, you know, different biases, like a recency bias or a novelty bias, it's a really easy way to just have an absolute comparison. You know, you start to look at percentage changes and then it's influenced by who your treatment, you know, how many users saw the experiment and, but at least, you know,

• 38:11Speaker 01

  an absolute number is, is easier in my mind to start comparing. Again, there are doubt, you know, there are pitfalls with it, but we find that that's a pretty useful way.

• 38:20Lenny Rachitsky?

  That lesson comes up a lot on this podcast and that approach to experiment. So yeah, you're good. You're in good company. A quick tangent. If there's not an answer to this, no problem. Coming back to the idea of just like experimenting like crazy and not creating a product that nobody wants to use anymore long-term. Is there an example of an experiment that was positive that you all decided, no, we don't actually think this is what we want. And the product they ended up not shipping.

• 38:46Speaker 01

  You know, retention doesn't only work on the streak, although you know, you would, you would think we did most of our work is the streak. We've touched a lot of different surfaces over the years. And there was one experiment that we launched that, you know, we talked about XP earlier. In the lesson, the only UI elements are a progress bar at the top and then how many hearts you have. Right? So we keep it really simple. And this very much speaks to the design, you know, philosophy of Duolingo, which is simpler UI is better. And we decided, hey, let's add XP in there. And so let's show your XP ticking up as you're going, you know, through a lesson. That's going to make the user feel good. It's going to give, you know, show you what you've earned. You're going to be less likely to quit. All of these good reasons to do it. And then you finish the lesson and then we'll show you've collected all this XP.

• 39:29Speaker 01

  And it won. I mean, the hypothesis was a good one. But we realized, and I remember having this conversation with Luis, is like, cool. This is our most important screen in the app. It is our lesson. It is where users learn. And the focus here is on learning. And now you've added this other thing up there to distract, you know, that could be distracting for users. And I think the question, you know, we talked about roadmaps and strategy here. The question that he had for me, and I didn't have a good answer for at the time, was like, so what else are you going to do with this? Like, what's your iteration ideas? Where's this going to go? Is this going to make the, you know, lesson experience more gamified? Or, and, and, and what we realized is that, like, honestly, it was kind of just a, you know,

• 40:09Speaker 01

  an easy engagement win idea, but we had touched our most, uh, you know, sacred space in the app to, to do that. And so that was a case where it's like, yeah, it was a nice win, but we had added that UI element. And, you know, at least at the time, it was less clear what we would do with it. And we realized that like, long-term, it was just going to get in the way. And we'd rather, for simplicity's sake, pause that, you know, shut it down and keep the lesson, you know, to be the, a little bit of a learning sanctuary it was. Now, it's funny, nowadays, I think we actually have enough XP-based mechanics and fun things that we can do that like, I think actually a lot of our, um, you know, the, the beliefs about the in lesson experience have changed.

• 40:51Speaker 01

  So something like that could work, but at the time, you know, didn't feel good to keep that around.

• 40:56Lenny Rachitsky?

  That is an awesome example. Uh, hopefully we have time to talk about how the team operates. Where my mind goes is like, oh, but you have all these PMs and teams that want to show impact and the performance reviews and all that stuff. And you're shipping, you're not shipping something. They're like, oh, look, we did a win. So I want to chat about that later, but let's keep going on things you've learned and things that didn't work on the journey.

• 41:15Speaker 01

  The, the other thing that, that I'll call out with the, the streak is, you know, it's like, we have the, the, the image of the streak is this flame, right? And, you know, we have the streak flame and it's, it's very much core to our iconography. It's important to acknowledge that that's a metaphor for a retention mechanic, like the idea of keeping a flame lit. And again, if you've, I think we've, we've established the flame as, you know, for a lot of users as sort of their understanding of a streak, which is great, but there's a lot of people. You know, in different cultural contexts and different, you know, uh, stages of life where the idea of like keeping a flame lit to show your commitment to something makes less sense. We did some UXR in India many years ago, and this was something that just like did not resonate

• 41:58Speaker 01

  at all there, which was, which was a really interesting learning. And that's something it's like, again, depending upon what your user base is, like, the more global UXR you can do to understand how users are actually understanding and experience your feature, the better because you just, again, encounter insights like this. And so even our screen design, you know, we used to have a flame. It was just, it was mostly this flame that would like light up every day. But again, it was like an indication of a metaphor for a mechanic. And when we redesigned it, we did this, Kurt, our, one of our animators, did this awesome odometer animation where it's like your number would tick every day. It like, kind of like looked good, but from a product perspective, what was cool is we actually focused the design on the screen to, to show

• 42:39Speaker 01

  your number going up. And then it would say, you know, like seven day streak, eight day streak. And I think that as you're thinking about designing around a streak, don't get too bought up, you know, or caught up into like, what is this, you know, like the beautiful story that you're trying to tell at the expense of it being a really comprehensible feature. And so as you're thinking about product design, making that product design a clear distillation of this is what we're actually tracking, you know, form should follow a function here, you know, was a, was, it was a learning for us. And you'll see that now at a lot of places where we're showing streak, we're, we're really leading with the number, not necessarily the, the flame.

• 43:17Lenny Rachitsky?

  That's all, that's a theme that I'm hearing again and again is clarity. Don't obsess with making it too thought like clever and don't ever think it just like clarity has a big impact.

• 43:29Speaker 01

  Clarity also doesn't have to come at the expense of delight. And this is something where, you know, you hit a milestone and Duo gets the, you know, it becomes, we call him a phoenix duo, and he becomes awesome and, you know, lights on fire. And I think there are things that you can do to still make the experience really exciting and delightful and celebratory. And, and I would, I would not lose that, but just don't do it at the expense. And I think it's also about figuring out for what, you know, you can get away with doing more of this for users who are deeper into their streak experience than users who are starting where it's like, your goal for the one day streak users, just to make sure, do they understand how this feature works? I mean, even something, again, just like another random experiment, at the bottom of the streak screen, we have a calendar.

• 44:12Speaker 01

  And over the years, it just looks more and more calendar-like. And that is simply because we find that the more we make it look like a calendar, days on top, you know, little circles, the check, like the more we make it look like calendar, the more that people realize, hey, this is a day, a daily mechanic. And so, think about the screen holistically, but every single thing that you're doing on the screen, how can you use it to communicate? What is the point of this feature? How does it work?

• 44:37Lenny Rachitsky?

  This episode is brought to you by Coda. I use Coda every day to coordinate my podcasting and newsletter workflows. From collecting questions for guests, to storing all my research, to managing my newsletter content calendar, Coda is my go-to app and has been for years. Coda combines the best of documents, spreadsheets, and apps to help me get more done. And Coda can help your team to stay aligned and ship faster by managing your planning cycle in just one location, set and measure OKRs with full visibility across teams and stakeholders, map dependencies, create progress visualizations, and identify risk areas. You can also access hundreds of pressure-tested templates for everything from roadmap strategy to final decision-making frameworks.

• 45:19Lenny Rachitsky?

  See for yourself why companies like DoorDash, Figma, and Qualtrics run on Coda. Take advantage of this special, limited-time offer just for startups. Head over to coda.io/lenny and sign up to get six free months of the team plan. That's coda.io/lenny to sign up and get six months of the team plan. coda.io/lenny. I imagine one of the biggest wins was just giving people flexibility along the journey, like streak freezes and all these things. Is that, is that a big vein of opportunity discovery?

• 45:52Speaker 01

  It is, it is great. Actually, I'm going to show you the, one of the most thoughtful gifts that anybody has ever given to me. This is our Duolingo Serenity, our streak serenity prayer, my colleague, Antonia.

• 46:03Lenny Rachitsky?

  It's like knitted, right? It's like-

• 46:05Speaker 01

  For me, it's amazing. And so it says- Luis, grant me the serenity to accept the flexibility I need, the courage to reach perfection when I can, and the wisdom to celebrate regardless. And that actually is like kind of our strategy with the streaks. Love the show and tell, by the way. That was great. Yeah, well, I guess for, you know, podcast listeners, we'll have to, you know, get an image somewhere. The, uh, this idea of like flexibility versus perfection and then regardless celebration is core to how we think about the streak. Cause you know, I think for the streak for us, it's very much a bend, not break. Uh, you know, I, if you're going to miss a day, I'd rather you come back, you know, having not, you know, having missed that day to an intact streak.

• 46:46Speaker 01

  But if you don't have to miss a day, I'd much rather you don't, I'd much rather you come back, uh, and, and use the app every day. So that, that, that thing on flexibility though, that's almost certainly been the biggest, you know, from a mechanic perspective, the biggest DAU driver. You know, one of the earliest experiments we ran was going from, you used to only be able to have one streak freeze. And then we let you have either two or three. So we tested two different arms.

• 47:10Speaker 01

  It was an, again, another huge DAU win. This actually is funny. It was something that, and this is again, kind of a whole, a callback to that growth model post from, from Jorge. It actually was really bad for KIR because we were basically saying, hey, you can take a day off, you know, and that's okay. But it was really good for, this is going to be like Alphabet soup, IWAR, an active, weekly active user retention, return rate. So basically users who had taken a day off, we were getting them to come back more at higher rates. And so it made up for our losses in KIR. But effectively what this meant is that, you know, why two streak freezes work better than one was, I don't know. Sometimes people just need a lot more flexibility than one day.

• 47:49Speaker 01

  But one of the, again, the really interesting insight of this experiment was that three streak freezes was actually no better than two streak freezes. And there were two competing things here. And I think this is important if you're going to build a streak, you know, to figure out what your flexibility mechanic is. We are getting more users to return after longer times away to an intact, you know, to an intact streak. But if you start taking three days off from any habit, it's just going to be less likely that you return even four days later. And so we had these competing things where users might, more users might be returning to a streak. A lot of users were also just not coming back. We were training them to, you know, take more time off. So that flexibility, what's the right amount of, I mean, we've, again, this is another area we've run. Hundreds of experiments on what is the right number of flexibility?

• 48:35Speaker 01

  What is the right amount of flexibility? And we, we are constantly surprised here. We, we don't, I, I still don't have the answer for at every point in your streak journey, how much flexibility you need. One thing that I can say with certainty though, is give more flexibility when a user is starting their streak. Again, one of our biggest streak freeze experiment when I feel like I'm constantly saying this, one of our biggest wins, but they all were really, really big. One of our biggest streak freeze wins was when you start a new streak, we give you two streak freezes. Again, it's so funny to think back. It's like, how are we not doing this to begin with? But at the time, the streak freeze was kind of an overly gamified mechanic. You had to buy them with gems. That's our in-app currency, you know, because we wanted the whole idea of, you know, this,

• 49:19Speaker 01

  to feel like you, like it was really, you know, something you earned that, you know, there was a little bit of pain to getting that streak freeze. And so we tested though, what if we just give users when they start off their streak, two streak, streak freezes? And holy smokes, did that win. And it's sort of obvious now, you know, in retrospect, but if you have a one or a two or a three day streak, it's really easy just to let it die and restart. You know, again, you need to get to seven days. Well, we've seen in the data for it to really lock in. And so giving users more flexibility so it's harder to lose their streak initially. And then conversely, and this is what we keep learning. Eventually, once people get on long streaks, you kind of don't want to give them as much flexibility.

• 49:59Speaker 01

  You know, because there's a lot of times where, yeah, users don't, and I'm like this. I've got like a 400 day streak. Note that that is a lot less time than I've been at Duolingo. I have lost and restarted streaks a lot of times in my time at Duolingo. But you start getting along streaks and you really care about this feature. You really care about your streak and most people, as long as you're not like backpacking through, I don't know, you know, the, the back country of Utah, you know, you'll, you'll be in a place where you can get service. And so figuring out. Where's the, you know, who is the user that actually could use Duolingo and not conditioning them to start taking days off that they didn't otherwise need to do is, is important to figure

• 50:43Speaker 01

  out sort of where that line is for, for your future.

• 50:46Lenny Rachitsky?

  This is fascinating. You can also buy a streak, right? Like with money. Is that, that's a feature, right?

• 50:51Speaker 01

  Yeah, you can. It's funny. This is, this is also something that we buy.

• 50:54Lenny Rachitsky?

  Yeah, you can buy. Or freeze, sorry, not a streak.

• 50:56Speaker 01

  Yeah. So you can, you can buy a streak freeze. And the way it works is you can buy gems and then you can use those gems to, to buy a streak. And this is something we wrestle with. We're actively working on an experiment right now that's having a small hit revenue, but it's a really nice win for retention. And I think it's actually worth thinking about from day one as you're building a streak. Do you see this more as a monetization feature? And do you see this more as a retention feature? What's the role of monetization in this? What's the role of retention? I think for us, it started out much more organically. And so we have a lot of like monetization hooks that again, as the retention PM, I would love to get rid of. But again, it's sort of part of how the streak works right now. And so we always have this tension of, hey, if we start to make

• 51:37Speaker 01

  it harder to buy streak freezes, then fewer people buy them, you know, buy gems to buy them. And so there's this more convoluted, you know, series of impacts that happen.

• 51:48Lenny Rachitsky?

  Yeah. No, I love that. I love that. People wanting to buy streak freezes like the ultimate sign of how much streaks matter.

• 51:56Speaker 01

  Yeah, it's streak, streak freeze is the other big one that we've, that we've recently demonetized or, or introduced a free option for is getting back a, a lost streak. So you started losing streak. We had a feature in the day, you know, back in the day called streak repair. We give you your streak back. You had to pay gems. But what we found out worked way better was a feature called earn back. And this is basically where you would have to do a certain number of lessons as long as you came back within, you know, a, a window soon after losing your streak. Do a few lessons and we just give you your streak back. And it was such a retention winner. And again, what we thought about was it feels like you've earned it so much more when you've done, like you deserve to have

• 52:40Speaker 01

  your streak back. We haven't cheapened the streak because you've done something. And in this sense, this idea of cheapening the streak is something like from a philosophical philosophy of the streak. From a philosophical level, we wrestle with all the time of. Cool. We're giving out more streak freezes. At what point do we cross the line and users start to realize their streak means nothing? Now, everything that we've seen, users are totally cool with using streak freezes and still thinking about the streak as this meaningful thing. But my co-lead, Antonia, who made that awesome cross-stitch for me, she is sort of the keeper for us of the sanctity of the streak. And a lot of times as we, and I think this is really important to have as you're thinking about building your streak, you can almost always get engagement wins up to a certain point by just cheapening the streak, making it easier to extend,

• 53:25Speaker 01

  letting users have more flexibility. But you kind of got to hold the line at some point. It's not clear where that line is. And once you, like, you talk about one-way doors or two-way doors, there's a point where you go too far and it's a one-way door. And all of a sudden, those users, those nine million users on one-year streaks don't care about their streak anymore. And that is, I don't know, again, retention PM perspective, that'd be an extinction level event for us. I don't, I don't want all of these users to stop caring about their streak. And so to have somebody who is invested in the sanctity of the streak, and you know, for us, it's Antonia and Luis, he's very good about this, is really important, just so you make sure you don't go too far.

• 54:06Lenny Rachitsky?

  That's an awesome insight. So to protect, and push notifications, I think, are another example, this in general for companies, like how much is too much? Because everyone's just like, let's just send another push. It's fine. Just do one more. And I, so your solution to that is a person is like the keeper and the gate, almost the gatekeeper, plus the founder of how far is too far.

• 54:25Speaker 01

  That, it's, yeah, it's, it's good if you can, if you can have that. I think push notifications are also easier because, you know, there's a lot of things you can do around, all right, we'll set a budget cap for how many notifications we'll send, you know, you can, you can-

• 54:36Lenny Rachitsky?

  Just like a creative policy.

• 54:38Speaker 01

  Yeah, policies. But I think with a lot of things, it's, it's hard, at least for the streak, it's harder to create policies for in the same way. A lot of it has to be done based on feel. And so you kind of just got to use your best judgment at times.

• 54:49Lenny Rachitsky?

  Sweet. Okay. Any other, maybe like one or two more lessons from this journey of what streaks has become today?

• 54:55Speaker 01

  I mean, I can, you mentioned notifications. I've mentioned this a few times. It's funny, you, you tend to think of like exactly as you say, ah, you can just always send another notification. It's going to be some win and at some point, you know, it'll, it'll be a bad experience, but it's tough to see that. There's actually a notification that we, so we send two notifications related to your core streak each day. The first is a practice reminder. We send it, and this is actually an interesting insight, 23 and a half hours after you practiced the day before.

• 55:20Lenny Rachitsky?

  Whoa.

• 55:21Speaker 01

  That is the line.

• 55:22Lenny Rachitsky?

  Twenty-three and a half, okay.

• 55:23Speaker 01

  So basically, if you practice at noon today, we'll send to you at 11:30 a.m. tomorrow. And we have done-

• 55:31Lenny Rachitsky?

  Because it's like, assuming they are free in that time the day before, maybe they'll be free the same time.

• 55:35Speaker 01

  And we actually moved, we used to let users set this practice reminder time and, you know, our thinking was, cool, you're gonna say 7:00 p.m. That's when I really want to extend my streak each day. And then you know what? I said this to somebody with two kids. Life gets in the way. Life always gets in the way. And when you think you're gonna practice, will change, your life will change, whatever. And what we realized is the best indicator of when you should practice was, when did you practice the day before? We could almost certainly get more detailed. We have tried a bunch of ways to have much more complex logic. And what always wins is 23 and a half hours.

• 56:07Lenny Rachitsky?

  That's so interesting. Revealed behavior versus stated.

• 56:09Speaker 01

  Exactly. So, so again, we send this practice reminder 23 and a half hours later. The other thing that we'll do though is we'll send it, what we call a streak saver. And this is at 10 o'clock at night, if you have not extended your streak, we'll send you a message saying, "Hey, you know, like, it's, it's your last chance. This is, this is it if you don't extend your streak." And you would think that like, that's kinda spammy. That's, that's kind of annoying to get a notification from an app at, at 10:00 p.m. But what we found is because people care about their streak, their streak is this good thing that they attach positive emotions to, that they don't really want to lose, that notification reminding them, "Hey, come back and..." Like, people see this, uh, by and large, as a positive notification and not a negative notification.

• 56:53Speaker 01

  Obviously, it serves our purposes well of getting users to come back and not lose their streaks. But again, I think if you can think about your notification strategy related to, what is the feature that it's tied to? How do users perceive that? You can almost certainly get a, not get away with more, but, you know, you could be thoughtful about notification load and when to send notifications. And again, for us, this like late night message, that's also highly impactful, super good, you know, is actually something that could be perceived as spammy, but a lot of our users really do. Somebody who- It's often late at night and I work here and I'm like, oh, forgot to do my, you know, I was thinking about Duolingo all day. You know, here it is 11:15 and I saw it done at that message is really powerful.

• 57:36Lenny Rachitsky?

  Yeah, it has saved me many times. I totally know that message and I love that it's like a late night message from an app. Very rarely do you actually are happy about that. And I love that this actually is a good example where like.

• 57:50Speaker 01

  It's really, it's really funny. All of the stories that you hear about people extending their streak. You know, if you look around the Duolingo party, uh, you know, where it's like 10, 11:30, 11:45. All the Duolingo employees that are like doing their lesson at the last minute. You always see these like pictures of people in the club doing or like at a concert doing Duolingo. And yeah, cause it's like, otherwise that you're going to use a streak freezer. God forbid you will lose your streak.

• 58:14Lenny Rachitsky?

  It's so funny. Okay. Anything else? And if there's like more than one more, definitely share. But any other really interesting lessons or wrong turns or insights?

• 58:22Speaker 01

  You know, I talked about streak freezes and we've done a lot with streak freezes. But I think if you're going to make flexibility a thing, it's probably also useful thinking about how do you celebrate perfection? Uh, and so we have a feature that we have, it is the simplest thing in the world. It's called perfect streak and it's just if you don't use a streak freeze for a few days. We make your streak look gold and we make your little progress bar on the calendar, um, just look a little bit nicer. There's no reward for doing it. You don't get anything other than this nice little indication. And it is awesome. It is, it is, it is, it is a simple feature. It is ultra not complex. And it is really powerful, not only for getting users to, you know, as, as a bit of a reward to be, hey, you know,

• 59:05Speaker 01

  get to seven days, you know, without using a streak freeze and you know, your streak becomes perfect. But it's also a really nice indication of users who aren't using streak freezes. Here is the thing that if you, uh, you know, if you don't use a streak freeze, which again, candidly, I would love for you never to use a streak freeze. If you don't use a streak freeze, your streak will stay, you know, perfect. It's funny. We, we actually just, you know, we're constantly, you know, responding to bug reports, uh, about the streak. You know, it is, I swear to God, we, we have that, we have the best infrastructure around this feature because it is so important. We had an employee who lost her. Like a four month perfect streak. And you know, it was a big deal for her because she, you know, and because she like did her lesson as she was crossing international dateline.

• 59:50Speaker 01

  There was like a bunch of stuff going on that was like, it was just kind of weird in our backend. But like, people start to care about perfection as much as they do their streak. And you know, for that person, it was, it was, it was a big deal when they lost their perfect streak. And so, you know, this is just an example of like, if you're going to, if you're going to go after flexibility, um, which is good. Finding a way to pull users back into perfection is a really important counterweight to have.

• 1:00:13Lenny Rachitsky?

  What I'm imagining is you guys need like an Amazon style chatbot that just gives you the streak back. It's just like, okay, here you go.

• 1:00:19Speaker 01

  We have very much, so we have, if people lose their streak, you know, there, there's ways to get in contact with us. But we've actually thought about that where it's like, okay, we should just like build a self-service feature. And if you're, if we think that your excuse is good enough, whatever, we'll just.

• 1:00:34Lenny Rachitsky?

  Yeah, yeah.

• 1:00:35Speaker 01

  Because again, it's for us. I'd much rather you be on, you know, be on a streak than, you know, have lost it, particularly if.

• 1:00:42Lenny Rachitsky?

  But it also can't feel that easy. I love this. I also love this point about just the power of the animation and user experience having impact. That's really interesting. Is that something you find often just like make, like celebrating and making it feel really amazing without like copy or, you know, or like any features? Just like, holy, you're awesome.

• 1:01:02Speaker 01

  This is another thing where it's like, when users care about the feature, using not only, uh, animation, haptics, sound effects. Using, and it's funny, we don't have sound effects on the streak. This will probably something we'll look at in the not too distant future, but like haptics are like something we have done a lot of testing.

• 1:01:18Lenny Rachitsky?

  Like the phone vibrating.

• 1:01:19Speaker 01

  Yeah, exactly. Your phone, you know, like there being a really cool haptic pattern as you extend your streak. All of this stuff wins and it's cool because I think it wins. There's a few reasons. One is it just makes you feel good, right? You know, you, you get some cool moment in your streak and, and, and we celebrate you. We celebrate you in this visual way and your phone's buzzing. It just like feels awesome. The other thing it does is that like. Causes you to pause on that screen. And I think there's this desire as you think through a lot of, you know, SPMs think through like, oh, how can I get users through this funnel as painlessly as possible? You know, I talked about good friction earlier. There's a lot of times where I don't, I want you to stop. I want you to stop and like land on the screen. You gotta be careful not to do this for too many screens, right? But like, for the one

• 1:02:00Speaker 01

  big ones, sometimes I just want you to pause there and enjoy the moment. Because if I can get you to enjoy the moment more, you're going to care more about your streak and you're going to be coming back tomorrow. And so animations that are cool and that cause you to like really soak it in, haptics, you know, that feel good, all of that comes together to make you really focus on that moment. All of that just gets users more connected to their streak. So animation in the right times works well. And it's something we've had win quite a lot.

• 1:02:29Lenny Rachitsky?

  Who designs the haptic stuff? Is there like a haptic designer?

• 1:02:33Speaker 01

  For the longest time, it would be a product designer. Or it initially started as like the engineer would be like, all right, you know, would cobble together haptics based on what they felt good. Then it became a product design role where they would kind of use their best judgment. We actually just recently acquired an animation studio, Hobbs, in Detroit. And now they are the sort of keepers of, you know, they're do a lot of motion design work. Haptics very close to that. And so they do a lot of that. I do remember trying to hire for a while a haptics like contractor, like haptics design. And it was the saddest hiring I've ever done. Because it was just like, I don't know, like, it was such a specific, like, I just went through a lot of people who, you know, it's just a really tricky space

• 1:03:18Speaker 01

  of like, kind of sound effects, kind of motion design, sort of technical.

• 1:03:22Lenny Rachitsky?

  Yeah, such a unique role.

• 1:03:25Speaker 01

  Very unique, specific skillset.

• 1:03:27Lenny Rachitsky?

  Right. And there's very few apps that really need this deeply. So you're almost creating this person.

• 1:03:32Speaker 01

  Yeah.

• 1:03:33Lenny Rachitsky?

  That is fascinating. I don't want, I'm gonna, that's like a whole podcast on its own. By the way, I was gonna say, as you're talking about this, I love that it's a win to celebrate people that don't lose their streak. Like, you introduced this way to make it flexible, and that's a big win. And then you could go the opposite direction of if you don't use this feature, you also feel even better.

• 1:03:51Speaker 01

  Well, and it's funny, you, like, you talked about the danger of feature blow. We sort of talked about the danger of feature blow. This is actually something I'm constantly thinking about with this. Like, we have the streak, but then we also have the perfect streak. And we can count how many, we count how many weeks you've had a perfect streak. Well, all of a sudden, we have two streak numbers that are kind of competing with each other. It's funny, we actually don't introduce the concept of a perfect streak until after you've hit seven days. And some of this is just because the cognitive load of additional streak features, a lot of our like cooler streak features, you gotta get on a long enough streak. And not to say we haven't tested it, because we have, because we've tested everything, introducing these features earlier. But what we've found is that pretty universally, they lose when we introduce too many things, too many concepts to users

• 1:04:36Speaker 01

  too early in the experience. It's just hard for them to manage.

• 1:04:39Lenny Rachitsky?

  Okay, sweet. I know that we can go down this track for hours and hours. There's endless learnings about all the things you all have done along the journey. I'm going to shift to talking about how your team operates. So there's a lot of threads you touched on of just how a team can do this so well. Ship 600 experiments, as you said, continue to find opportunity. What are some maybe lessons or advice you'd have for folks that are like, oh, wow, I want to work more like this from your team's experience? How do you use your team to operate that folks can learn from?

• 1:05:13Speaker 01

  Yeah, maybe just a little bit of context. We're Duolingo cares a lot about metrics. So most of our teams are metric based teams. So we do the most work with streak. But you know, the metric, what we really care about at the end of the day is cur and DAUs, because we see that DAUs hit cur. And so when you can be really laser focused on my goal each quarter is to make this metric go up. I think it's much easier to make sure that you're working on the highest ROI thing. I think when you think more about like, oh, I want to make this feature better. I think it's easier to get lost in what better means and how you think about better. And so I do think that like having a really strong career focus, you know, as a team on, you know, what is the metric that I'm caring about and how is that directing my efforts is.

• 1:05:58Lenny Rachitsky?

  Versus feature oriented. So basically your teams are structured around a metric slash a goal slash outcome versus we own this feature or this.

• 1:06:07Speaker 01

  So we need retention owns streak, I guess, but that's only because we've seen streak drive cur better than any feature, but.

• 1:06:17Speaker 01

  We are not, I mean, we have this, you know, IAP hook with our streak freeze purchases. There are other teams that work on, you know, that can and have worked on the streak because it's not ours to say, no, no, we do all the iterations here. We just know that it drives our metric better in the same way that like leaderboards. You know, we have a team that focuses on how much time you've spent. We want users to spend more time on Duolingo so they're learning more. Leaderboards is the best vector for doing it. So that team does a lot of leaderboard work, but every now and then I have an idea that I think will be highly retentive. And I will go in and I will pitch to them and then we'll do some change to the leaderboard to make it more retentive. And so, but I, but I do think having that clear metric of we're trying to drive curve, not we're trying to just make this feature better.

• 1:06:59Speaker 01

  Helps at least make sure, you know, give the team clear marching orders and that focus, I think is really good for prioritizing backlog.

• 1:07:07Lenny Rachitsky?

  Cool. This is a really important point. This is the same way Airbnb worked when I worked there for a long time is it's here's a goal that we want your team to be responsible for. You could work on any product you need to hit this goal. As you said, often like various products are most connected to what you're doing. But what you're describing is like, even though a team's kind of like, I imagine you own it from a bug perspective and you're kind of like, are the shepherd of this part of the feature because it hits your goal. Helps your girl most, but any other team can come in and be like, hey, Jackson, we need to work on some streak stuff to help with learning. You know, like go for it. Does that, just a tangent there. Do they like work really closely with your team if they want to do some work in the code? Is it like, how does that work?

• 1:07:48Speaker 01

  Yeah. If, if, if you're, again, this is where I say there's soft ownership. We're not against teams doing things to the streak. But if we're going to do something, given, you know, we probably have multiple quarters worth of a roadmap around the street. I say probably we do, multiple quarters of roadmap for what we can do to the streak. If other teams want to come and mess with it, okay, we got to just figure out how is that going to work with, you know, what, what our plans for the streak were. How do we make sure a lot of times when teams are coming in thinking, hey, let's do this to the streak, they're like in context that we might have. And so there's as much of like a much simpler version of what we're doing now, a bit of a knowledge sharing of saying, all right, well, this is what we think about the streak. This is what we've seen work, hasn't worked. How does that influence some of the hypothesis that you have? And so I think getting that really, making sure the juice is worth the squeeze.

• 1:08:32Lenny Rachitsky?

  Good old fashioned product management work right there. Cool. What else is interesting about how you all operate and how you all work to achieve this sort of success?

• 1:08:41Speaker 01

  Again, my, my team lead runs is, Antonio runs like the most, you know, a really process. If you're going to run this many experiments, you have to be really process oriented and really thoughtful about which experiments am I going to run when? How is that going to set up the next one? We, you know, there's, there's heavy Jira automation. I think sometimes the Atlassian suite makes my eyes bleed, but like, there's a lot of times where that degree of process helps the team unblock engineers and make them move really fast. And so making sure that you have really good process around how are you going to run so many experiments? It's, you know, it's, it's, it's worth investing in.

• 1:09:17Lenny Rachitsky?

  Can you follow that thread? Actually, just what do you, when you say that, what does that look like? What are some elements of that process to make this work efficiently?

• 1:09:25Speaker 01

  All the way down to like a really detailed roadmaps around, all right, we're running this experiment is based on the results of this experiment or my, you know, the hook into an element of this feature. How do we make sure that we're lining up implementation on this so that as soon as this thing runs and we're ready to go, we can start rolling out the next one? You know, I hate features just sitting around and us not, again, continuing that thread. So it's not just thinking about what's our engineering bandwidth, but also what's the design bandwidth to make sure that we have the next iteration of this feature ready to go? You know, we're planning months out as we think about these feature iterations, even small ones, you know, feature iterations, because again, you just, you lose, when you

• 1:10:07Speaker 01

  lose cycles, you know, not pushing on a feature, it's just sort of lost opportunity. And so everything from manage, you know, being thoughtful about engineering roadmaps to design roadmaps to product roadmaps, all of that needs to come together in a system.

• 1:10:19Lenny Rachitsky?

  So essentially mapping dependencies across function and you're saying in Jira, you can do this?

• 1:10:25Speaker 01

  You can do a lot of it in Jira. There is a non-zero amount of Google Docs that we have that sometimes does things.

• 1:10:32Lenny Rachitsky?

  Yep.

• 1:10:33Speaker 01

  A little bit. I don't know. Sometimes it just looks a little bit nicer. It's a little more possible. But Jira is our, it is where the mother load of process is.

• 1:10:42Lenny Rachitsky?

  Great. Okay. What else?

• 1:10:43Speaker 01

  Like another thing that I'll, that I'll just say is like, we really resist the urge to do the big V1. And I think this is, you know, I shared the, the street goal example where a lot of times when we're exploring something, we will say, okay, well, like, that's cool. How do we strip away a bunch of stuff and figure out what our core hypothesis is? And then just ship that thing first as a V1? Cause it's easy, and I've found this time and time again. It's easy to add things to features that make them win. Like I've worked in retention engagement long enough. I can like add, I know enough like things to pull and bells to add and whistles and you know, to make something win. But you know, there's a lot of times where it's like, cool.

• 1:11:26Speaker 01

  Well, then it won because of all the whistles you added, not because of what your core hypothesis was. And a lot of times, if you can just really simplify what the feature is, it's also much easier to ship. It's easier to design. You're not designing for a whole system. You're designing for, you know, something, something much simpler. And so getting everybody to think that way ends up allow, you know, allows us to end up shipping faster, shipping simpler, you know, designing faster, getting faster approval, getting insight, and then doing what I talked about with street goal, being able to run iteration after iteration after iteration, add these things iteratively. And then now you, not only by doing this, are you able to move faster, but you get confidence at each step of the way that, hey, my series of hypotheses, you know, is actually borne out.

• 1:12:11Speaker 01

  Or if it's not, cool, then we're going to drop that part of the feature and then just ship what actually matters.

• 1:12:17Lenny Rachitsky?

  If I can try to summarize kind of the broad lesson so far that I'm hearing, and maybe you, you would have shared this, but I'm just thinking like, if I were to try to design a company to operate the way you all operate, you essentially map all the levers that drive the business. So you have kind of this mapping of all the metrics that drive up to growth and daily active users. You, KRR ended up being the biggest specific metric to move to drive growth long-term. So there's like imagining a tree of all the opportunities you could work on. You found like, this is what is most connected to our growth long-term. You basically just start mining.

• 1:12:59Lenny Rachitsky?

  I don't know if mining is the right metaphor, but just like looking for things that move that specific metric. You just like look and poke and explore. And then, once you find one, you just go real deep on trying a lot of different. You could come up with a hypothesis and a strategy of here's how we think we can do this and how we can move this. And then you just try a bunch of stuff. There's also this element of the Arrested Development quote, "There's always money in the banana stand," comes to mind, where it's just like, keep working on, see, there's more, there's going to be more opportunity at this.

• 1:13:28Speaker 01

  When I joined Duolingo, the PM that I took over for Anton, who used to lead the retention team, I remember saying, "Dude, the streak, like, it just counts up. You guys have been testing on it for years. How much more work can we do on the streak?" And he was like, "Jackson, you child." He didn't say exactly this, but this is how I felt it. Like, Jackson, you child. There is, we're not even 30% of the way optimized. And four years later, I say that with like such conviction, we are so far away from, I mean, we've made a ton of strides, but we are still so far away. And every quarter where we ship a ton of, you know, wins and, you know, improvements to the streak, it just continues to prove to

• 1:14:08Speaker 01

  me that like, there is so much more to be done. So I think your framing of it is, and I would say there's a lot of thought that goes into, you know, again, you know, I talked about the strength of the hypothesis that you have, you know, you have to have as you start to build out larger, you know, future strategy. I do think it's really important to not just do a bunch of random stuff, but do it with intent, you know, with a goal in mind. Otherwise, you do end up in these local, you know, local maximas. But yeah, I mean, there's still a bunch of stuff that we haven't tried that, you know, I think we have high confidence in, you know, working out. And so we'll, we'll keep doing that.

• 1:14:44Lenny Rachitsky?

  Are there any other, say, lasting lessons from this journey that if someone were to try to operate this way, build streaks into their product, anything you'd recommend?

• 1:14:55Speaker 01

  Yeah, I really do think it starts with, you know, streaks are an engagement hack. You know, you can, you can make your app more retentive. I'm almost positive, almost every app out there can make it more attentive. It is loss aversion. That is, you know, again, armchair psychologist Jackson, like, it's just a human, a thing that works on humans. But if your, if your app is not something that users want to use every day, or whatever, you know, cadence you want your app to be, you know, to work on, it's going to be, you're only going to get so much from that streak. And honestly, it's probably going to distract you from what really should matter, which is making your app something that people want to use every day. And so if you start focusing on the streak, but you haven't made that a enjoyable experiment or experience,

• 1:15:41Speaker 01

  You're just gonna waste a lot of time, honestly. And so I think making sure that you have your core loop of your app figured out that it is giving value to users is something that they want to come back to every day. That really sets the stage for something to layer a streak on. So resist the temptation if you haven't, you know, if you don't think you've reached that point to go too hard down the, you know, the path of streak.

• 1:16:03Lenny Rachitsky?

  That's a really good point, just like a streak is not going to solve your problems if people don't actually care about the core value you're providing.

• 1:16:09Speaker 01

  No, and honestly, it'll probably cause more problems if what you end up focusing on is how do I make the streak highly engaging, but your app isn't. I mean, you're just, you're wasting time that could otherwise be, you know, better spent on solving more, more critical problems. So that's, that's one learning. You know, the other thing that I'll say is, and we, we met with one of our board members, Bing, Bing Gordon, a few weeks or a few months ago, rather. And he had this comment where he was just like, the reason why users care about your streak so much is because you care about your streak so much, you being Duolingo. Like, the reason why users care about our streak so much, because Duolingo cares about the streak so much. We're like, what do you mean? Well, he's like, well, after every session, you see a big streak screen and it's animated cooler than almost any other screen in the app.

• 1:16:54Speaker 01

  And then sometimes you see some other screens and there's all these other feet. Like, you don't let a user forget it. You talk about them in messages. And, and so I think it's worth thinking about, look, if you're gonna build a streak and then you're gonna con it off into the corner of your app, uh, you know, where users aren't gonna see it, like, they're probably not gonna care about it as much. And, which might be fine, because there might be other lovers that you think are more important to pull on. But there's a reason why, you know, we focus as much on the streak, you know, as, as we do. And that's because we want it to be top of mind for, for users. And it's not by accident then that users start to care about it. And so I think just as you're thinking about building the streak, making sure that you're giving it the visibility it deserves, if you want it to have the kind of impact that Duolingo has, um, you know,

• 1:17:37Speaker 01

  it's sort of an important hierarchy principle to, to think about as you design things.

• 1:17:42Lenny Rachitsky?

  That's such a good point. Like, you look for cues to the app of tell me what I should pay attention to, what's important. If you're just like, fire explosions, you've hit a streak. Oh, maybe I should pay attention to this feature. And then the push notifications obviously encourage you there too. Uh, anything else along those lines?

• 1:17:58Speaker 01

  Maybe final thing is, look, we ran so many tests on our Duolingo streak to figure out what worked. I mean, we have, we have a, we have a philosophy at Duolingo of test it first. You know, we are a lot of times willing to test things. I really think that if you're gonna, you're gonna try to introduce a streak or you want to improve on the streak you have, like, don't get too caught up in the, the, the philosophy of, of everything. I mean, make sure your hypotheses feel like they're good, but my recommendation is just try things. And this is again, you, you said it earlier. It's like, this is most human psychology as anything. And as soon as that becomes the case, like, you kind of just got to understand what users respond to.

• 1:18:38Speaker 01

  And the easiest way to do that is to stop spending time, you know, batting around ideas in a, in a conference room and just try some stuff. Um, so huge recommendation to like, if you're going to invest in a streak, try and figure out what works through testing with users, um, rather than trying to get it perfect on the first try.

• 1:18:57Lenny Rachitsky?

  Say someone's listening and they're like, should we do streak? Cause it's worth doing. What's your take on just like the chances that a streak feature would be helpful to another consumer?

• 1:19:06Speaker 01

  I'm, I am, uh, well known for saying in the company that I think every streak, every team, every app could, could benefit from a streak. Now, how you implement it is very different. And I think you gotta like, what is your user's use case? Like if they're going to come use, I don't know, tax software. Okay. You know, you know, now that I say this tax software would be a hard one, but maybe it's all about, you know, you know, you need users to come back every day during the tax season, uh, or how many times? I don't know. You know, now that I say this out loud.

• 1:19:34Lenny Rachitsky?

  Times you upload your, uh, your.

• 1:19:36Speaker 01

  That is a hard, yeah, that is a hard use case, but I, the, the vast majority of, of, of, of companies, I think have a good idea of like, all right, here is my ideal use case. I want users to come here three times a month. That, that would be ideal, you know, or four times a month. You can build a streak to work. I mean, Peloton has, has weekly streaks because the idea of doing a Peloton, you know, uh, workout every single day is hard for a lot of, was hard for this user during COVID, you know, it's just like every now and then you get on the Peloton. That was great. But the idea of a weekly streak was something that I could keep up. And so I think figure out what your usage pattern is, is a user, and then build your streak around it. But. You know, as long as you're not, you know, the like a really, again, the tax example was probably

• 1:20:20Speaker 01

  a good counterfactual, but as long as you have some degree of frequency in your, in your use, I think almost anything can have a, can have a streak.

• 1:20:29Lenny Rachitsky?

  So Duolingo, it's again, a $14 billion company. This feature possibly the most contributing factor, other than the core, you know, product to that level of success and market cap. And it's hard to imagine another just feature of a product that has had this much impact on, on growth and revenue and building this sort of business. So I love that we spent this much time on it. A motherload, a motherload of advice and insights. So thank you again for putting it.

• 1:20:59Speaker 01

  Very fun.

• 1:21:00Lenny Rachitsky?

  With that, we've reached our very exciting lightning round. Are you ready?

• 1:21:04Speaker 01

  I'm, I'm, I'm ready.

• 1:21:06Lenny Rachitsky?

  First question, what are two or three books you've recommended most to other people?

• 1:21:10Speaker 01

  All right. I'll start with a guide to Midwest conversation. So I'm based in Kansas City. I'm a proud Midwesterner and us Midwesterners talk in a certain way. I think, you know, you hear about Minnesota nice, but we tend not to say what we mean. And it is a very funny primer into what Midwesterners actually mean when they say what they say. So highly recommend reading that.

• 1:21:33Lenny Rachitsky?

  I like that they give that to people. Just like, here's what I might be telling you, which you may not read.

• 1:21:38Speaker 01

  But my, my wife is German and I gave it to her.

• 1:21:41Lenny Rachitsky?

  I can see German being the opposite of that.

• 1:21:43Speaker 01

  Very different. Another book, uh, this is a good one. Uh, Fate is the Hunter. So this is a really cool book. It, it's a memoir of one of the early commercial airline pilots. And it is wild to hear the stories about what flying was back in the day. You know, I'm a former management consultant. I flew every week for almost six years and I never once had to worry about, am I going to make it to the other end of this flight alive? That was not the case back then. And so some of the stories about what it used to be like to be a pilot on some of these planes before modern aviation technology is fascinating. It makes you really appreciate what we have.

• 1:22:22Lenny Rachitsky?

  It feels good to read a book like that, being a software PM or engineer, whatever, like how different that life is.

• 1:22:28Speaker 01

  Hardware is hard.

• 1:22:31Lenny Rachitsky?

  Oh, man, it's not haptic design. Okay, next, unless there's any other books you're gonna share. Okay, great. What's a favorite recent movie or TV show you really enjoyed?

• 1:22:40Speaker 01

  So I have two kids. I watch a lot of Bluey. It's really good. I swear it's it brings me no shortage of joy. But adult show that I heard or show not meant for four year olds that I have watched. I just finished the latest season of Emily in Paris. Man, wonderful. I realize it's not the highest brow of television, but just like beautiful people in beautiful cities solving problems that are not, you know, earth shattering. Sometimes it is nice to just tune out. Also, I'm learning French on Duolingo. A slight plug for the app. I can understand a lot of the French that is being spoken. And there is no better joy than having invested as much time as I have in French and actually being able to use it. So huge fan of Emily.

• 1:23:23Lenny Rachitsky?

  That is so funny. What a fun Venn diagram of interests. My mother in law loves Emily in Paris. I saw someone tweeting about like, what visa is she on? How is she still in Paris?

• 1:23:33Speaker 01

  Yeah, you best just not ask questions. There's a lot. There's a lot of questions to this show that are better than unasked.

• 1:23:39Lenny Rachitsky?

  Do you have a favorite product you recently discovered that you really like, other than Duolingo?

• 1:23:43Speaker 01

  Last week I went to Home Depot and I bought a new ladder and ladder innovations, you don't think, you know, of often, but you can make one of the legs go a little bit further than the other leg. And as somebody like myself who has a house that is built on a slight slope, every time I go up on my ladder, I take my life in my hands. But with this ladder, I'm always even I cleaned my gutters twice last week, just because of how awesome this ladder has has how much this ladder has changed my life. So ladder innovation, I don't think it gets talked enough about. And so I'm happy to give it the spotlight it deserves.

• 1:24:17Lenny Rachitsky?

  I appreciate you doing that. This is the first ladder recommendation we've had on the podcast. Two more questions. Do you have a favorite life motto that you really find useful and work around life that you share with folks?

• 1:24:26Speaker 01

  This probably will not be much of a surprise based on how I've talked about our willingness to test things, but you miss 100% of the shots that you don't take. I'm a big fan of just trying things, even if you're Possibility of success is not 100 because you learn a lot along the way. So.

• 1:24:44Lenny Rachitsky?

  Final question. Do you have any fun traditions at Duolingo amongst either the PM team or the company in general? That might be delightful to share.

• 1:24:53Speaker 01

  We have way too many traditions to count.

• 1:24:57Speaker 01

  I will share the weird tradition that we do at every retention stand up. And this started during the pandemic. You know, we obviously used to stand up in person and then when we went remote, we did this thing where whoever's the last person to go would count down three, two, one. And then we'd all try to clap at the same time, which was kind of fun and dorky, but we fell in love with it and four years later, we're still doing it. Recently, we've added, we all say yee-haw in unison afterwards. I can't tell you why, but trying to synchronize a clap via Zoom and then all shouting yee-haw. I did this in a phone booth the other day and after I came out, someone told me, you know that those aren't as soundproof as you think, but you know,

• 1:25:43Speaker 01

  when you get a good opportunity to give a yee-haw, you kind of can't pass up on it. So.

• 1:25:47Lenny Rachitsky?

  I love these little things like they're so, you know, they sound so minor, but they're such important elements of team culture and tradition. And so important for PMs to find ways to just have fun and do something ridiculous.

• 1:25:58Speaker 01

  I will say it took a while to get people behind shouting yee-haw. But now that we have people doing it, you can't, you can't take it away from them. We all, we all love it.

• 1:26:09Lenny Rachitsky?

  Oh, man, I, I called our all hands for a while, y'all hands. Feel free to steal that.

• 1:26:14Speaker 01

  You get it. You get it, Lenny. Yeah.

• 1:26:15Lenny Rachitsky?

  I get it. Jackson, this is incredible. I feel like people are going to listen to this with notebooks and just like, okay, here, here's a bunch of ideas we should try with whatever we're working on, whether it's streaks or not. Thank you so much for being here. Two final questions. Where can folks find you online if they want to reach out, learn more, learn more about Duolingo? I know you're hiring product managers, so share more there. And finally, how can listeners be useful to you?

• 1:26:37Speaker 01

  Yes, you can find me on LinkedIn. That is where most of my online social media is. So Jackson Shuttleworth. And then how people can be useful to me. Yes, as you said, we are hiring, we're actually hiring for my team. Are you interested in thinking about streaks as much as we do? You know, we might be the right home for you. So please, you know, you can apply on our website. We're also hiring for a number of other product management roles and they're all as thrilling as this work is. And then, you know, I'm always interested about how other companies have implemented streaks and what they've learned. And so what I'd say is if you're a company who's implemented a streak, maybe in a different way than Duolingo has, or you know,

• 1:27:19Speaker 01

  you've found a whole ton of success and you know, another vector, another element to the feature that we didn't talk about today, I would love to know more. I used to catalog basically every streak I found out there. And as it's become more of a popular feature, it's just been hard to keep up on. So, you know, if you have interesting streak insights to send my way, I would love to hear them.

• 1:27:41Lenny Rachitsky?

  I love that. A collection of all the best ways of doing streaks. Jackson, I just want to say congrats to your team and you for having so much impact. This is like the dream of a lot of PMs and teams is to see this much impact and continue to ship wins. And so, congrats. Nice work.

• 1:27:57Speaker 01

  Thank you very much.

• 1:27:58Lenny Rachitsky?

  Retention. And with that, Jackson, thanks so much for being here.

• 1:28:01Speaker 01

  Yeah, thank you, Lenny. This was, this was a lot of fun.

• 1:28:04Lenny Rachitsky?

  Same. Bye, everyone.

• 1:28:07Lenny Rachitsky?

  Thank you so much for listening. If you found this valuable, you can subscribe to the show on Apple Podcasts, Spotify, or your favorite podcast app. Also, please consider giving us a rating or leaving a review, as that really helps other listeners find the podcast. You can find all past episodes or learn more about the show at lennyspodcast.com. See you in the next episode.