How does Bill Gates inspire students to change the world? Tune in here to find out. Gates is kicking off a college tour today with a speech to students at UC Berkeley. He will talk about the big challenges facing the world today (poverty, health, energy, climate change) and what can be done to tackle them. The key is innovation in both the public and private sectors, using technology in smart ways, and changing people's economic incentives. Gates and his wife Melinda are spending much of their time and money on these issues through their foundation. But you don't have to be a billionaire to try to make the world a better place to live. In partnership with the Gates Foundation, we are proud to present his speech in the live video after the jump.