I understand the frustration of Prince George’s County Executive Rushern L. Baker III over low school performance. I see why he wants to take power away from a sometimes ineffective school board. All over the country, conscientious leaders like Baker are looking for ways to improve learning, particularly for poor kids.

But county and state officials should not overlook a crucial fact. In some ways, teaching and learning are improving in Prince George’s schools. They should not mess with what is working.

Those debating the Baker plan don’t seem to realize that administrators and teachers have increased significantly the number of Prince George’s students taking college-level courses like Advanced Placement and International Baccalaureate. More students than ever before are passing those exams, which are written and graded by outside experts. The educators are changing the culture of low expectations. Any new approach that disrupts their work would be a setback.

Since 1997, I have recorded the growth of AP and IB courses and tests in each of the nearly 200 Washington area public high schools, including the 22 in Prince George’s County. In 1998, the first year I published a list of the most challenging high schools in the country based on AP and IB test participation, only one Prince George’s school, the celebrated magnet Eleanor Roosevelt, was on the list. Later this spring, when The Washington Post publishes the new national list, 11 Prince George’s schools will be on it.

These schools, like Eleanor Roosevelt, are now in the top 10 percent of U.S. schools on the Challenge Index: Bowie, Central, Flowers, Crossland, DuVal, High Point, Laurel, Northwestern, Oxon Hill and Parkdale. They have brought more students into tough courses in math, biology, history and other subjects and have strengthened teaching so more pass the exams.

This takes time, energy and patience. These schools have improved despite several changes of superintendents and school board members. Leading the unheralded movement are teachers and principals, not policymakers. Educators working in schools have provided a challenge and given their students extra time and encouragement to prepare for it.

The percentage of Prince George’s students passing the AP and IB exams is still below national averages. But they are improving. People who have not spent much time in low-income schools often tell me that teachers should not be doing AP until their students are ready to pass AP exams. The hundreds of teachers I have interviewed in such schools across the country tell me that’s wrong. You can’t improve student success in AP unless they are taking AP.

Students who flunk the exams tell me they are still learning more than they would in regular courses. Each year, AP teachers improve their craft and raise the level of instruction for the next crop of students.

Northwestern High School in Hyattsville, where 70 percent of students are low-income, increased the number of AP tests taken from 307 in 2011 to 484 in 2012, while raising the passing rate from 16 percent to 29 percent. Oxon Hill High School, which is 45 percent low-income, jumped from 490 to 754 AP tests in that same period, and it raised its passing rate from 15 to 17 percent.

I hope Baker understands how important these gains are. As far as I can see, the AP and IB classes are among the most promising parts of the school system. Do what you want with the school board, but keep those teachers and administrators happy. And while you are telling them how much you support them, you might ask them what they think is the best way to move the entire school system to a new level.

For previous columns, go to washingtonpost.com/class-struggle.