Griffel has emerged as a leader in the DIY learning movement. A self-taught developer, he started teaching at Skillshare in 2012, which turned into One Month. The Y Combinator-backed startup has shown 15,000 students how to build websites and apps from scratch. One Month is expanding globally and into non-tech classes. He’s also a partner at GrowHack, a hacking shop for startups, and a teacher at General Assembly.