For many years I wrote a regular newspaper column about schools in Prince George’s County, Maryland. I noticed that one of the high schools had been recognized as having more African American test-takers and passers in Advanced Placement than any other high school in the region, and I was curious to know what they were doing. When I visited the school, I thought the first thing the principal would do would be to tell me his AP teachers were amazing and give me a tour of the classrooms. He did eventually — and the teachers were great — and I was able to watch kids extract DNA from fruit and discuss the American Revolution.

The first thing the principal did, however, was take me into the office of his assistant principal, who was in charge of the school’s schedule; point to a giant chart on the wall-sized whiteboard that showed when every class in the school was taught at what day and time and by whom and where; and say something to the effect of “that’s the reason for our success.”

I look back on that moment as the beginning of my education about systems. I wasn’t prepared, so many of the details of what the assistant principal subsequently told me went over my head. The chart, as any school person can say, was the master schedule of the school. I remember listening to the assistant principal tell me that it was built around the semester-by-semester expansion of AP classes and how he had hand-scheduled hundreds of AP students to ensure they got all their classes. As he walked me through the chart to show me how he juggled all the priorities of the school to focus on giving more students the opportunity to be exposed to and master advanced material, it began to dawn on me that the master schedule was a concrete expression of the school’s values.

My education has continued through more than a decade of visiting unexpected schools. In each one, teachers and leaders have talked about the issues their very vulnerable students bring to school and the systems they have put in place to address them, from master schedules to counseling groups.

These schools not only put in systems but also continually evaluate them so that they can continue and expand the ones that work or change or jettison those that don’t. Here’s a small example of what I mean: The teachers and leaders of Elmont Memorial High School once noticed that their ninth-graders were having difficulty making the transition from middle to high school. They used the master schedule to set up a “ninth-grade academy” in which groups of students would share teams of teachers who could collaborate on how to teach individual students. “It worked. For a while,” said John Capozzi, the former principal. That is to say, for a year or two, ninth-graders were more successful than they had been. They started slipping again because new issues had emerged. Elmont changed the schedule again.

In a sense this is the scientific method in action: See a problem. Analyze the cause of the problem in the light of established research. Develop a hypothesis for how to solve it. Set up a system to reflect the hypothesis and measure results. Assess to see if the system solved the problem. If it solved the problem, see if there is a way to strengthen or extend the solution. If it didn’t solve the problem — that is, if the system failed — that is not a cause for blame; rather, it is part of the learning process en route to developing another hypothesis and another system. As such, the work is never done. As Capozzi said, “If you think you’re done, it’s time to get out.”

To read more about how educators use the scientific method to drive improvement in their schools, read my new book from Harvard Education Press, Schools That Succeed. Next week, I’ll share a story from Artesia High School, another unexpected school featured in the book. (You can read previous posts about unexpected schools here.)