Millionaire industrialist Eli Broad made his fortune by building two businesses from the bottom up. Now he spends his time giving that fortune away. Broad takes an active hand managing his Los Angeles-based trio of foundations. He has made big investments in furthering medical research and promoting the arts, but his most important commitment is to reforming the nation's public education system. BusinessWeek Staf edotpr, Jessi Hempel talks with Mr. Broad about how he plans to change the nation's schools for the better and why running a foundation is a lot like managing a business