Suppose a teacher in an urban high school wanted to do more than survive. Suppose he wanted to do the job right. Sharpening his pencil and firing up his calculator, Mr. Gleibermann decided to find out just how long that would take. ********** TWO WEEKS after a year of urban high school teaching, I sat down to calculate how many hours a week it would take to leave no child behind. That's no child out of 150, since last year I taught five classes a day, averaging 30 students a class, in a San Francisco public school. I added methodically: teaching five sections of two separate courses every day, tutoring all the students who needed extra help to pass, evaluating papers and projects, and collaborating with other teachers to shape the school's academic program. The total was 140 hours per week. Discovering this mathematical absurdity softened my long-standing despair. Throughout my teaching career, I worked inhuman hours and yet wondered if I was giving enough. Only by putting the raw statistics on paper did I find an antidote to self-blame. I finally discerned that when a great many of my students fall by the academic wayside, the blame belongs not to me, but to a system that would require a teacher to work 140 hours a week to support all his students. How did I arrive at such a frightening figure as 140? The deciding variable is the time required to respond to the academic needs of each individual student. Consider writing as a test case. In a couple of hours I can craft and deliver a focused and engaging writing lesson on thesis design, embedding quotations, or parallel construction and have students edit one another's essays and take notes from a PowerPoint display. But if the goal is to ensure that each of my 150 students can apply the lesson to essay writing and take a step toward passing the writing portion of the state exit exam, no elegant lesson with any group of 30 students will ever succeed. Having high school sophomores learn to write by observing me construct a coherent paragraph on an overhead screen is the instructional equivalent of teaching them to ride a bicycle by showing videotapes. Writing is a complex mental journey. Children need a mentor to navigate the way. If they are going to succeed, I will need to coach many of them individually outside the regular school day. Conscientious teachers who are determined to open academic doorways for all students have been aware for decades that they lack the resources to meet the needs of well over 100 students. But recent state and federal education policy has brought this condition to public awareness. The goal of No Child Left Behind appears admirable: by the year 2014 every child in the nation will test to proficiency in core math and literacy skills. In addition, most states now require seniors to pass an exit exam to receive a diploma. California's high school class of 2006 was the first to fall under this requirement, following a delay four years ago when more than half of the first cohort failed. However, as we investigate what schools need to reach these ambitious goals, we publicly expose a difficult truth that teachers have long experienced one arduous day at a time. Our school system is based on a 19th-century factory model that cycles 150 students a day through a teacher's classroom, a process that was never intended to ensure that all students achieve high-level skills. But we have yet to promote alternative models that might point us toward universal success or to provide resources for public education that would appreciably reduce teacher workload. The current testing regimen and stricter teacher credentialing requirements of recent education policy do not even touch the deeper structural problem. Until we begin to provide resources that, at a minimum, allow teachers to work with far fewer students, any teacher who aims for universal success prescribes for himself eventual mental exhaustion. …