As chief executive of the Chicago Public Schools, Arne Duncan closed more than a dozen of the city’s worst schools, reopening them with new principals and teachers. Now Duncan, President Obama’s education secretary, wants to take school turnaround efforts nationwide on a scale never tried before, though he faces many obstacles, reports the New York Times. In speeches and interviews, Duncan said he would press local authorities to close thousands of the country’s worst schools, the dropout factories where only a tiny fraction of students are reading at grade level, and reopen them with new staff members. Duncan appears to have the money to drive the effort. Experts estimate the cost of overhauling a failing school at $3 million to $6 million. Duncan controls $3 billion in the economic stimulus law that could go to school turnarounds, and the administration’s 2010 budget requests $1.5 billion more. Still, "closing a school is the most difficult task any superintendent or school board can attempt, and not many succeed," said Terry Mazany, who watched Duncan’s school makeovers as chief executive at the Chicago Community Trust. Duncan wants to see 250 schools closed and reconstituted next year. That would mean dismissing thousands of teachers next spring, hiring replacements, and opening newly reconstituted schools in fall 2010…