Learning from mistakes and constantly improving products is a key in all successful companies.

We all have the chance to create a world where extreme poverty is the exception rather than the rule.

Well private money can take risks in a way that government money often isn't willing to.

When I was trying to figure out why lives have improved so much in the last 300 years, where we've gone from a third of kids dying before 5 to - by 1990 it was down to 10% - now it's down to 5%. And saying why, over all history, there were smart people, but that number didn't change. Average life span didn't change. What's magical about what's been deemed the Industrial Revolution? It's really energy intensity.

The belief that the world is getting worse, that we can't solve extreme poverty and disease, isn't just mistaken. It is harmful.

Don't let complexity stop you. Be activists. Take on the big inequities. It will be one of the great experiences of your lives.

Technology must be implemented as part of a thoughtful, holistic approach to education transformation that includes teacher training, relevant curricula, parental involvement, and programs for children that fill unmet needs for basics like nutrition and health care.