(Update: Adding more on opposition to Core, where Duncan spoke) U.S. Education Secretary Arne Duncan told a group of state schools superintendents Friday that he found it “fascinating” that some of the opposition to the Common Core State Standards has come from “white suburban moms who — all of a sudden — their child isn’t as brilliant as they thought they were and their school isn’t quite as good as they thought they were.” Yes, he really said that. But he has said similar things before. What, exactly, is he talking about? In his cheerleading for the controversial Common Core...