The number of charter schools grew rapidly for a quarter-century after the first charter opened its doors in 1992. But since 2016, the rate of increase has slowed. Is the pause related to a decline in charter effectiveness?
To find out, we track changes in student performance at charter and district schools on the National Assessment of Educational Progress, which tests reading and math skills of a nationally representative sample of students every other year. We focus on trends in student performance from 2005 through 2017 to get a sense of the direction in which the district and charter sectors are heading. We also control for differences in students’ background characteristics. This is the first study to use this information to compare trend lines. Most prior research has compared the relative effectiveness of the charter and district sectors at a single point in time.
Our analysis shows that student cohorts in the charter sector made greater gains from 2005 to 2017 than did cohorts in the district sector. The difference in the trends in the two sectors amounts to nearly an additional half-year’s worth of learning. The biggest gains are for African Americans and for students of low socioeconomic status attending charter schools. When we adjust for changes in student background characteristics, we find that two-thirds of the relative gain in the charter sector cannot be explained by demography. In other words, the pace of change is more rapid either because the charter sector, relative to the district sector, is attracting a more proficient set of students in ways that cannot be detected by demographic characteristics, or because charter schools and their teachers are doing a better job of teaching students.