Luis Von Ahn

That means they haven't missed a day in the last year or longer.

Now, one fact about streaks.

What country do you think has the longest average streaks for an educational app?

It's Japan.

Of course.

Shortest average streaks?

Latin America, baby.

But we're fun.

Hey, we're fun.

Another important mechanism to get people to come back to your product are notifications.

On the one side, notifications can be really spammy and annoying, but in the case of an educational product, people actually want to be reminded to learn.

In the case of Duolingo, we have a very sophisticated AI system that

basically chooses when to send a notification and also what to say in each notification to maximize the probability that people come back.

Now, interestingly, even after all this sophistication, it turns out that the algorithm for choosing what time to send you a notification is pretty simple.

Do you know what is the best time to send people a notification?

I'll tell you.

It's 24 hours after they use the product last.

And there's an easy explanation.

If you were free yesterday at 3 p.m., you're probably free today at 3 p.m.

as well.