I usually make to-do lists with timelines, and pen and paper does the trick for me.

One fact we're particularly proud of is that there are more people learning languages on Duolingo in the US than there are people learning languages in the entire US public school system.

People are good at figuring out what's attractive, and computers are good at quickly searching and finding. You put them together, and bang!

If you get asked to do something that would take place down the road (say you get asked to speak at a conference that's a year away) and you wouldn't want to do it if it were taking place next week, then don't do it. This advice has helped me evaluate the opportunities that I truly want to dedicate my time to and those that I don't.

I co-founded Duolingo with the mission of bringing free language education to the world.

I watch a lot of TV. That's how I spend most of my time outside of work. If I had more time, I would fill it 100 percent with watching TV.

The current business model for language education is the student pays — in particular, the student pays Rosetta Stone $500. The problem with this business model is that 95 percent of the world’s population doesn’t have $500.