Capitalism has worked very well. Anyone who wants to move to North Korea is welcome.

It's fine to celebrate success but it is more important to heed the lessons of failure.

Students deserve great teachers. And teachers deserve the support they need to become great.

Teaching is the human thing, in terms of building the kids' self-confidence, so if we take the broad ways that we want to see society to be better, science can only provide certain pieces of that.

Cutting through complexity to find a solution runs through four predictable stages: determine a goal, find the highest-leverage approach, discover the ideal technology for that approach, and in the meantime, make the smartest application of the technology that you already have - whether it's something sophisticated, like a drug, or something simpler, like a bednet.

I have been struck again and again by how important measurement is to improving the human condition.

Having kids has been a fantastic thing for me. It's meant that I'm a little more balanced. In my twenties I worked massively, hardly took vacation at all. Now, I, with the help of my wife, I'm always making sure I've got a good balance of how I spend my time.