Research shows that there is only half as much variation in student achievement between schools as there is among classrooms in the same school. If you want your child to get the best education possible, it is actually more important to get him assigned to a great teacher than to a great school.

You know, I'm a big believer in touch and digital reading, but I still think that some mixture of voice, the pen and a real keyboard - in other words a netbook - will be the mainstream on that.

Teaching's hard! You need different skills: positive reinforcement, keeping students from getting bored, commanding their attention in a certain way.

We're creating this alliance, GAVI, that has helped buy the vaccines that were in the rich world but not getting to the poor kids, getting a very cheap price and figuring out the cold chain, getting the delivery right, and then funding research for new vaccines. A lot of them are coming along. We've got a meningitis vaccine out, got that through large parts of Africa. That has been a huge success.

The most amazing philanthropists are people who are actually making a significant sacrifice.

The most important work I got a chance to be involved in, no matter what I do, is the personal computer... I even knew not to get married until later because I was so obsessed with it. That's my life's work.

India has over 20 percent of the kids born in the world. And they move around a lot.