The green owl is not just a mascot. It is a guilt machine. People do their lessons because they do not want to disappoint a cartoon bird. And it works.
We treat engagement like a mobile gaming company, not an education company. If the lesson is boring, people stop. Boring is the enemy.
I grew up in Guatemala where access to quality education costs money most families do not have. Duolingo exists so that zip code does not determine what you can learn.
Free education is not a charity model. It is a business model. The 5% who pay subsidize the 95% who learn for free. Everyone wins.
A streak is the most powerful feature we ever built. People will do insane things to avoid breaking a 500-day streak. Loss aversion is a hell of a drug.
I invented CAPTCHA and reCAPTCHA before Duolingo. I have accidentally wasted more human time than almost anyone alive. Duolingo is my redemption.