John Danner has been a serial entrepreneur. The founder of NetGravity, the web’s first advertising server company, Danner took it public and sold it for $750 million. He then turned to a career in education. He co-founded Rocketship Education, a network of blended-learning charter schools, and then left a few years ago and founded his current venture, Zeal, which has the mission of crushing the cost of tutoring so that every student can have a personal math coach. I caught up with John recently to hear how the new venture was going and hear his evolving thoughts on the critical future of human capital in education.