Are charter schools helping students succeed? Many studies have contributed to answering this multidimensional question, including a recent Fordham Institute report highlighting the association between a rise in charter student enrollment share at the metro level and increases in math achievement. A recent set of city-level reports from Stanford’s Center for Research on Education Outcomes (CREDO) provides us with a new body of empirical evidence on student achievement in charter schools compared to traditional public schools (TPS). These CREDO reports are part of an ongoing series, the City Studies Project, tracking student performance in select cities’ public K–12 schools around the country.
CREDO releases these city assessments on a rolling basis, but a May release of three—Denver, Colorado; Memphis, Tennessee; and Baton Rouge, Louisiana—provides yet more evidence that urban charter schools boost the achievement of their students, and also includes scintillating findings about magnets, innovation schools, and other school models.
In each case, it uses student-level data from 2016 through 2019 to compare the progress of students attending charter schools with TPS, along with other schools of choice, further broken down along the lines of sex, race, poverty status, English language learner (ELL) status, and special education status. The researchers first compare each city’s student performance to state averages, and then compare the different organizational models within each city.
In Denver, the researchers found students posted stronger learning gains compared to state averages in both reading and math during the 2017–18 and 2018–19 school years. In 2018–19, Denver district schools (TPS) delivered 23 extra days of reading and 17 of math, while Denver charter schools delivered 54 extra days of reading and 60 of math. Innovation schools, district schools in an “innovation zone” that get extra flexibility from state standards, delivered 66 extra days of reading and 56 days of math.
Broken down by demographic characteristics, female students outperformed male students in every year and organizational category. Denver’s charter school Black student performance versus district school Black performance stands out, with 58 and 71 days’ growth in reading and math for charter schools, respectively, compared to 12 and 16 days of loss for district schools. Charters also posted stronger growth in learning for Hispanic and low-SES students, though Denver innovation schools stood out for their exceptional ELL student reading gains. Denver charters also delivered stronger results than TPS for special education students in reading, perhaps challenging the public perception that charter schools somehow “leave behind” special ed public school students, or boost their performance via these students’ exclusion.
Finally, CREDO presents some evidence that Denver charter schools managed by “CMOs,” or charter management organizations, see somewhat greater success in math than independently-run charter schools.
Moving on to Memphis, the CREDO researchers found students exhibited similar growth in 2017–18 and small losses in ’18–19 compared to state averages in reading, while holding pace with state averages in math for both years. It may be worth noting that, in Denver, average household income in 2018 was $64,000, close to state averages of $69,000; while in Memphis, average household income in 2018 was $39,000, considerably below state averages of $51,000. We should also mention that Memphis has an “Achievement School District” (ASD), designed to take schools in the bottom 5 percent of statewide test performance and, ambitiously, turn them around to reach the top 25 percent statewide. Memphis also uses “Optional Schools,” which screen students for academic performance, somewhat like exam schools.
In Memphis, in 2017–18 and ’18–19, these Optional Schools delivered the strongest returns, far exceeding statewide averages. District and charter schools clustered around the state average, with charters slightly outperforming TPS—though the difference wasn't statistically significant. Schools in the ASD underperformed state averages. The city’s Black students slightly underperformed state averages, though those in Optional Schools posted strong gains. The ELL students in the Optional Schools, however, saw strong gains in reading but significant losses in math, perhaps exposing an underlying flaw in Memphis’s ELL approach. And female students underperformed male peers to a greater degree than state averages.
Baton Rouge, finally, breaks down schools in TPS, charters, and magnets. On reading and math performance, magnet schools dominate, with around 100 more days of learning compared to state averages. Charters and districts return more moderate gains, with charters consistently outperforming TPS—though, like in Memphis, the difference wasn't statistically significant. CMO-managed charters moderately but significantly outperform independently-administered charters. Across Baton Rouge, female students outperform males, and Black students slightly outperform state averages. Hispanic students, however, do well in magnet and charter schools, but actually post losses in 2017–18 and ’18–19 in both reading and math for district schools.
So, what’s driving the differential performance of these school models? Though the City Studies Project does not draw many conclusions beyond presenting the data, it appears that within each city there is sorting of the student population into the most-demanding schools. In Denver, that seems to be charter schools, while in Memphis it’s the academic-screening Optional Schools, and in Baton Rouge it’s the in-demand magnet schools.
However, we should caution that this does not mean charter schools or other schools of choice take away from or diminish traditional/district public school performance. There’s a growing body of evidence that competitive effects between TPS schools and charter schools induce a rising tide that lifts all ships. And as the strong performance of special education students in Denver suggested, this sorting effect does not mean that charter schools boost their numbers by excluding special needs students.
SOURCE: “City Studies,” Center for Research on Education Outcomes, Stanford University, retrieved July 26, 2022.
Correction, August 15, 2022: This review previously gave the impression that charter schools in Memphis and Baton Rouge produced larger academic gains than traditional public schools. These differences in the studies, however, were small and not statistically significant. It also indicated that Denver charter schools outperformed the city’s traditional public schools on academic gains for English language learners, and for special education students in math; these differences, too, were not statistically significant. The review has been corrected to reflect these issues.