STUDENTS WHO attend charter schools in the District gained an extra 72 days in reading and an additional 101 days in math over the course of a year compared to their counterparts in traditional public schools. That’s essentially an extra half-year of school. Those impressive findings from a new national study attest to the dramatic improvement of the District’s charter schools and show that they are creating an environment where students can achieve.

A comprehensive study by the Center for Research on Education Outcomes (CREDO) at Stanford University showed D.C. public charter school students outperforming those in the D.C. school system. The results stand in stark contrast to 2009, when CREDO researchers found no difference in performance between the two groups.

Equally impressive is how D.C. charters, which enroll 43 percent of public school students, exceeded the performance of charters nationally. The 2013 analysis of student performance at charter schools in 25 states, D.C. and New York City showed gains for charters of eight additional days of learning in reading over conventional schools and about the same learning gain in math. The 2009 study showed nationwide charter school performance lagging regular school counterparts in both subjects, so the improved performance is significant. The improvement comes as greater numbers of minority and poor students with educational disadvantages are attending (and benefitting from) charter schools.

The willingness to close chronically failing schools seems to have made a difference in the learning gains. CREDO researchers said the jurisdictions that closed at least 10 percent of their charter schools — the worst performers — posted the best overall results. “Twenty-seven schools have closed their doors [since charters started in D.C.] and I guarantee that if they were still open D.C. would not show up in the CREDO report as outperforming,” Scott Pearson, executive director of the D.C. Public Charter School Board, said of the refusal to tolerate year-in-year-out failure.

There is, both on the local and national level, great disparity in the quality of charter schools, and much work still needs to be done. But the District has been fortunate to have a good law that ensures charter independence and a high-quality authorizer that has insisted on high standards and accountability. In that success story are lessons to be learned not just for other charter schools but for traditional systems as well.