BROCKTON, Mass. — A decade ago, Brockton High School was a case study in failure. Teachers and administrators often voiced the unofficial school motto in hallway chitchat: students have a right to fail if they want. And many of them did — only a quarter of the students passed statewide exams. One in three dropped out.

Then Susan Szachowicz and a handful of fellow teachers decided to take action. They persuaded administrators to let them organize a schoolwide campaign that involved reading and writing lessons into every class in all subjects, including gym.

Their efforts paid off quickly. In 2001 testing, more students passed the state tests after failing the year before than at any other school in Massachusetts. The gains continued. This year and last, Brockton outperformed 90 percent of Massachusetts high schools. And its turnaround is getting new attention in a report, “How High Schools Become Exemplary,” published last month by Ronald F. Ferguson, an economist at Harvard who researches the minority achievement gap.

What makes Brockton High’s story surprising is that, with 4,100 students, it is an exception to what has become received wisdom in many educational circles — that small is almost always better.