Even when different teachers' lessons are actually compatible, students often fail to recognize the convergence because the same things are said in different ways, and the teachers are too oblivious to spot and address the confusion. In her recent book, The College Fear Factor: How Students and Professors Misunderstand One Another, Rebecca Cox documents the damage such mixed messages inflict on community college students. One student Cox interviewed put her finger on the problem with unusual poignancy:

What is really right for a good paper? Everybody has their standards. So if Mr. Dobbs is teaching me, and he thinks this is a good paper, then what if I do what he told me to do, and I take it to another professor and maybe that's not his standards? And if my teacher says, "Well, it's not a good paper," what am I supposed to do?

So what is right? So that's very vague; there's no curriculum--I mean, is that what all the teachers think is a good paper? Or is that just his opinion?

Cox notes how difficult it is for a student to determine whether something a teacher says is "what all the teachers think" or just one teacher's opinion. This confusion often erodes students' "initial optimism" about education. They become cynical and disillusioned, and in many cases, even drop out.

Such curricular dissonance also does much to widen the achievement gap. The high achievers manage to synthesize the mixed messages on their own and thereby deepen their learning from course to course, but the rest do not. For them, education is not a cumulative process, but a bizarre obstacle course in which students must virtually start from scratch every time they enter a new course. Who can blame them if they come away believing that education is just a cynical business of learning enough to get past one teacher and then setting aside those lessons to meet the unrelated or conflicting demands of the next one?

Great teaching can't fix this problem as long as students are distracted by the discrepancies and contradictions between classes. In a New Yorker article some years back, Malcolm Gladwell unwittingly illustrated this point when he compared talented instructors to NFL quarterbacks. "There are certain jobs," he wrote, "where almost nothing you can learn about candidates before they start predicts how they'll do once they're hired. So how do we know whom to choose in cases like that?"

Yet as any sports fan knows, teams that have great individual athletes still lose when their stars work at cross purposes. Like losing sports teams, American schools and colleges depend too much on brilliant individual teaching performances instead of coordinating their teachers' lessons enough to give students a clear and consistent picture of how academic work is done. And journalists, politicians, and Hollywood studios support this misguided reliance on individual performance when they glorify individual difference makers like Mr. Keating in Dead Poets Society or Ms. Gruwell in Freedom Writers.