Two years after Congress made the federal government's largest one-time investment in the nation's public schools, the American Recovery and Reinvestment Act--the economic-stimulus package--has prevented massive teacher layoffs, spurred states to devise sweeping education overhaul plans, and invigorated the national conversation about turning…

A year ago, Arne Duncan was known as a long-serving urban district chief who had used his collegial management style to push innovation and close failing schools in Chicago. This week, he enters his second year as U.S. secretary of education pursuing a similar national policy agenda that could place him among the most influential leaders in his…