Luis von Ahn could have retired to a beach somewhere years ago. Best known as the CEO of the learning app Duolingo , von Ahn in the 2000s invented the captcha , those infuriating little online tests that force people to prove they’re not robots. But after selling his creation to Google in 2009, von Ahn didn’t waste any time launching his next venture: a company borne of his experience growing up in Guatemala, one that’s now among the most prominent education platforms in the world. Von Ahn’s mom, a doctor, spent all of her extra income to send him to private school, giving von Ahn opportunities that most of his peers never saw. It is, as he tells me in this week’s Big Interview, the reason he founded Duolingo more than a decade ago, with the goal of making high-quality education free and widely available. Today, the company reaches more than 130 million users worldwide , from immigrants learning new languages to celebrities like George Clooney .…