I usually don’t celebrate schools that fail to make my annual list of America’s Most Challenging High Schools. But a week before the 2017 rankings will appear in The Washington Post, a low-performing high school in the District has shown such exceptional improvement in teaching and learning it deserves special attention.

Eastern High School, east of Capitol Hill at 1700 East Capitol St. NE, got plenty of notice for its new building in 2010, the result of a $77 million renovation. School modernizations usually don’t change academic performance, so I ignored it.

During the 20 years I have been collecting data on high schools in the Washington area and nationally, Eastern has had one of the worst records. Few students participated in its Advanced Placement program, and those that did almost always failed the college-level exams.

[America’s most challenging high schools]

This year, however, D.C. Public Schools sent me a startling number from Eastern. In 2013, the school had begun an International Baccalaureate program preparing students for college-level exams even more challenging than those given by AP. Both AP and IB exams are written and graded by outside experts. In 2016, the D.C. information said, Eastern gave 62 IB exams, and 42 percent of them received passing scores of four or above on the seven-point tests.

I checked to make sure that was not a misprint. I cannot remember another instance in which an urban public school like Eastern, where just about all students are from low-income families, achieved such gains.

Even more important than the scores on IB’s three- to five-hour exams, requiring long written answers, was the system the school created to help students read, write and think at a depth rarely encountered in such impoverished circumstances.

Kate Ireland, director of global education in the D.C. Public Schools’ Office of Teaching and Learning, and Sah Brown, Eastern’s principal, described for me in a long email how they strengthened their students’ writing and thinking. The school district established IB-designed programs in three elementary and two middle schools. Eastern High educators spread word of the program to families of children headed for the school. They created the Accelerated Cohort at Eastern (ACE) for ninth- and 10th- graders who had shown “motivation and habits of mind to meet above-grade level academic standards,” Ireland and Brown said.

The ACE students those first two years take courses that demand more writing and conceptual learning than most D.C. students are used to. Just before the ACE students’ junior year when they begin taking IB courses, they attend a summer boot camp to get ready.

Eastern offers IB courses in language and literature, history, math studies, Spanish, visual arts, biology and theory of knowledge. Writing is woven into the program. Assessments in IB courses are based on “a mix of timed and untimed essays, research papers, projects, experiments, question sets and presentations,” Ireland and Brown said. “This enables us as teachers to build students’ writing abilities little by little and utilize the entire two years of the course to maximize student growth.”

Teachers stay for an after-school “Power Hour” to help students tackle difficult points. Such careful preparation, and the funds that support it, would be useful to other D.C. schools trying to raise achievement levels in AP.

Here is one sign of the value of IB. Parents in Montgomery County may spend as much as $864 for registration and exams for each child in the toughest IB track. The cost to IB families at Eastern is zero.

AP students at Eastern are also doing better. Their passing rate on the AP exams was 11 percent, way above the school average for the prior 20 years. If Eastern gives a couple of dozen more AP and IB exams next year, it will make The Post’s list. That is a nice recognition, but not nearly as useful as the reading, writing and thinking skills its students will take with them to college.