sal's -- the khan academy. sal's mission has been to make education more accessible. d at 100 million students across the world use the khan academy. i spoke with him as the back to school season is back in swing. >> it started as a family project almost 15 years ago when i was tutoring my cousin. word got around, and i found myself working with 10, 15 cousins. i started writing software for them, and that was the first khan academy so they could get practice. and then a friend suggested i make videos to supplement that. the videos, i just happened to put them on youtube, made them public for my family. my family told me they liked me better on youtube than in person -- [laughter] and more importantly, folks who weren't my cousins started to watch. fast forward by 2009, 2010, my day job, i was an analyst at a hedge fund, but i had trouble focusing because there was many tens of thousands of folks at the time who were using the resource. so i quit my day job, set it up as a not for profit, and in 2010 we got some of our first significant funding from the gates foundatio