The man charged with downsizing the federal role in public schools is a passionate policy geek who says his own teachers saved his life.

John King, who stepped in as education secretary Jan. 1, spent his free time in college designing curriculum modules on Puerto Rican history. As New York state’s education commissioner, he came under withering criticism for aggressive reforms that many teachers and parents said steamrolled their concerns.

The wonky and polarizing King now faces the most delicate task of his career, designing regulations for the law replacing No Child Left Behind, which pares back the education secretary’s authority and gives states broad flexibility in making decisions for students, teachers and schools. He could have a huge influence on how much sway over states his successors will have.

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