When people began telling me of J.E.B. Stuart High School’s decline, with scores plummeting and teachers leaving, I contacted Bill Horkan, a veteran math teacher at the Fairfax County school who is one of the most insightful educators I know.

Horkan said he sees some recent improvements. But both he and former Stuart math department chair Stu Singer said what happened at Stuart during the past several years was awful. Singer called it “education malpractice that can only be described as unconscionable.” Administrators who did not understand or did not care what happened in classrooms squashed the successful ideas of great teachers.

If that can happen to Stuart, it can happen anywhere. In 2005, President George W. Bush spoke at the school in recognition of its high achievement despite having mostly students from low-income minority families. Then-principal Mel Riddile was named 2006 National High School Principal of the Year.

Some of Stuart’s greatest progress had been in math. When the first Virginia state Standards of Learning tests were given in the late 1990s, Stuart’s math passing rate was the lowest in the county.

Singer and other faculty leaders were urged by Riddile to be creative. The math department’s first successful initiative was Algebra 1 Part One. Students doing poorly after first semester Algebra 1 transferred to Algebra 1 Part One for a spring semester, solidifying their understanding. The next year they took Algebra 1 Part Two. By 2005, Singer said, Stuart had the highest passing rate in the county on the SOL Algebra 1 exam, besting schools that had almost no low-income students.

Having built that foundation in Algebra 1, the math teachers created Double Block Algebra 2. Students who still had problems with math took two full periods of Algebra 2, giving them more time to work on basics. The second class consisted of only struggling students, defying the assumption that poor students would do better if mixed with good ones.

Horkan taught the second class. It turned out, he said, that in a class with good students “the struggling students would be afraid of answering the questions wrong” and stay quiet, inhibiting their learning. “When put in a class where everyone was struggling, the students were not afraid of being wrong,” he said. They talked, and learned, more.

In the second year of the program, 90 percent of students in the double-block classes passed the SOL Algebra 2 exam, higher than the county’s average rate.

In April 2008, after Riddile had left the school, Singer learned that a meeting of district officials kept secret from him had decided Stuart’s unique Algebra 1 and Algebra 2 programs would be abolished. Singer and Horkan said they thought this was in part because other schools were skeptical or envious of a low-income school with such scores, and didn’t check to see how it worked. I think the decision-makers weren’t so much jealous as they were lazy and misguided. In any case, math passing rates at Stuart dropped sharply.

After 40 years at Stuart, Singer retired in protest. Other Riddile-era programs were undercut. Parents began to complain. In a recent survey, as reported by my colleague T. Rees Shapiro, just 25 percent of Stuart staff rated school leadership as effective, more than 30 percentage points lower than any other high school.

That might be changing, Horkan said. The Algebra 1 program has been restored, and Double Block Algebra 2 will be back soon. The latest principal appears to be listening to faculty critics.

“Stuart High School parents, teachers and administrators are working together to promote the success of every student,” said schools spokesman John Torre. “Test scores are once again on the upswing at Stuart, with the math pass rate increasing by nearly 9 percent this past year.”

But as long as there are administrators who carelessly discard the work of great teachers, no school is safe from what happened to Stuart High.