Helen Moore of Detroit leads a group of protesters outside the federal courthouse in Cincinnati last Thursday. "Every school in the country would be affected," one expert said. "There could be a lot of litigation." After two years of struggling to pass any of his community college classes, Jamarria Hall, 19, knows this for certain: His high school did not prepare him. The four years he spent at Detroit’s Osborn High School were “a big waste of time,” he said, recalling 11th and 12th grade English classes where students were taught from materials labeled for third or fourth graders, and...