Karin Chenoweth, a former colleague at The Washington Post, has made a career of revealing why some schools succeed despite lack of funds, reputation and college-educated parents. In her latest book, she delves into the power of the master schedule, a device I have always considered a big bore.

That shows how stupid I am. Chenoweth, a writer-in-residence at the Education Trust, makes me feel a bit better by admitting that she, too, at first did not understand why the principal of a high school in Prince George’s County, Md., said his complex master schedule on a wall-size whiteboard was “the reason for our success.” Later she realized that this was where the school was changing average students’ lives by making sure they were scheduled into Advanced Placement classes that had previously been reserved for top students and creating new classes to support that AP learning.

The old system, Chenoweth said, sent this message: “Some kids are smart, and they get to talk about great literature, wrestle with historical dilemmas, learn foreign languages, and study knotty mathematical and scientific problems; other kids are not so smart and do remedial work that never seems to remediate. That is to say, they do low-level work that never helps them access higher-level work but just keeps them busy and bored.”

The beginning of the solution, Chenoweth said, is to change the master schedule, a process seldom given the importance it deserves. Her incisive book, “Schools That Succeed: How Educators Marshal the Power of Systems for Improvement,” exposes the unseen indicators of improvement in school routines.

When a new principal arrived at Artesia High School in Los Angeles County, he identified all students who had been scheduled for consumer math, pre-algebra and general math and put them into Algebra I instead. Then, Chenoweth said, he did something else essential to smart scheduling. Bumping them up to algebra would not cure their deficiencies in arithmetic, so he added math support classes to their schedules.

Equity 2000, a College Board experiment at seven school districts in the 1990s, showed that putting every student into Algebra I by ninth grade at the latest produced a significant increase in the number of ninth-graders who passed Algebra I. But extra support is often crucial for any such acceleration. The most successful national effort to provide it is the Advancement Via Individual Determination (AVID) program, invented by San Diego English teacher Mary Catherine Swanson to leverage the power of great tutoring.

Chenoweth reveals why approaches such as AVID work so well. At Elmont Memorial High School in Nassau County, N.Y., and at Artesia High, she found that administrators did not rely on the cheaper and easier solution of having support classes after school. They knew that until students believed that extra time led to more achievement, they were reluctant to stick around after the final bell. So those schools built the support classes into the regular school day, just like AVID. They were not optional.

Chenoweth also exposes some great scheduling goofs. At one elementary school, “every class had 15 minutes to go to the bathroom in the morning and afternoon, thus using up half an hour a day — ninety hours a year — that could otherwise have been used for instruction. Not only was it a huge time waster, the master schedule assumed that all kids needed to go to the bathroom at the same time,” Chenoweth writes.

By the end of Chenoweth’s master schedule analysis, I was dizzy with the complications of how to set up classes just right. Creative scheduling, for instance, can make it possible for teachers to learn from colleagues by observing one another’s classes. But their own rooms must be covered by substitutes capable of keeping lessons moving forward. Those of us who remember our own substitute teachers know that is not so common.

Next time I visit a school, I will insist on looking at the master schedule. Chenoweth has unearthed a secret of great schooling, but it takes extraordinarily ambitious, and persistent, administrators to make it work.