Eric Nadelstern is a professor in the Education Leadership Program and director of the Summer Principals Academy at Columbia University’s Teachers College. In 2011, he retired from the New York City Department of Education as deputy chancellor for the Division of School Support and Instruction, overseeing instructional and operational support to the city’s 1,700 schools. He began his career teaching English as a second language at his alma mater, DeWitt Clinton High School in the Bronx, and held a wide variety of positions of increasing responsibility during his 39 years with the city school system. In 1985 he founded International High School, a small school for recent immigrants that became a model replicated at 11 New York City schools and was the basis of citywide efforts to replace large, problematic schools with smaller, more effective ones. He is the author of "10 Lessons from New York City Schools: What Really Works to Improve Education," published in 2013 by Teachers College Press.