Proud parents and grandparents are sharing photos of their kids’ first day of school. And as students head back, many states are pushing back—telling the Obama Administration that its federal education plan isn’t right for their students. Anyone who has taught in a classroom knows how different children are from school to school—even from class to class. Teachers understand that the content, methods, and evaluations they use will differ depending on the makeup of the class. A teacher might teach her 9:40 a.m. Algebra II class differently than her 1:40 p.m. Algebra II class. And she’ll make that decision based...