Income differences correlate with achievement gaps in our schools. Charter schools are closing those gaps.
This is the first article of a two-part series on charter schools. The second will appear on 11/20/24 and is titled "What Donors Should Know About Evaluating Charter Schools."
There is glaring student achievement inequality in America’s public schools. Rigorous evidence suggests that “a substantial portion of the unequal education outcomes that we see between richer and poor students is related not to home, but to what happens in school.” Charter schools are reducing that inequality by closing achievement gaps between groups and improving outcomes for all students.
Since 1991, 46 charter laws have created 8,000 schools and campuses that enroll 3.7 million students, around 7.5% of all public school students. Enrollment in these independent public school of choice that are accountable for results is increasing while traditional district school enrollment is decreasing. For example, over the five years from 2019-2020 to 2023-2024, charter enrollment grew by around 12% or 393,000 students, while district enrollment decreased by around 4% or 1,750,000 students. Around six out of 10 (58%) charter schools are in urban areas, with the remainder in suburbs (25%), rural areas (11%), and smaller towns (6%).
Has this charter growth harmed traditional public schools? And how can we be sure that charter schools are meeting the needs of students who most need help?
Over the last 18 months, four national and two state reports on charter schools were released. In what follows, I summarize those reports, providing more evidence of a dynamic, self-improving charter sector that reduces student academic inequality.
Recent Studies of Charter School Effects
Let’s start with a few basic facts. Charter schools employ around 251,000 teachers, who are younger and more racially and ethnically diverse than traditional district school teachers. Additionally, charter schools consistently enroll more students of color and students from low-income families than traditional district schools. Currently, seven out of 10 (71%) charter students are students of color compared to around half (54%) of district students, with six out of 10 students receiving free and reduced lunch compared to half in district schools. Hispanic students are the fastest-growing student group in America’s charter schools.
What’s more, they help this diverse student body overcome academic gaps. A 2023 report from the Stanford University Center for Research on Education Outcomes found that the typical charter student made gains in reading and math test scores greater than the typical district student. Charters added 6 days of learning in math and 16 days in reading. Charter management organizations operating multiple schools were especially effective, regularly “returning more positive, and often gap-busting, results,” the report says.
Similar findings come from a 2023 report by the Massachusetts Institute of Technology and the National Bureau of Economic Research. It summarized thirty years of evidence for lottery charter schools—schools where more students apply than can be accepted, requiring lotteries to determine who can enroll. This gold standard scientific research concluded that “Existing evidence shows that charter schools can improve academic achievement and longer-term outcomes like four-year college enrollment, particularly among lower performing students, non-white students, low-income students, and students with disabilities.”
Remarkably, these educational gains ripple out from charter schools to entire school districts. Another 2023 report in the Journal of Public Economics examined school district data from 1995 to 2016, analyzing the effects of charter schools on standardized tests and graduation rates, including the impact on students attending nearby public schools. It found that growing charter schools’ market share by 10% increased math and reading scores and high school graduation rates for all students within a district, not just for one particular student group. This “rising tide” bespeaks the competitive effects of charter schools, including replacing underperforming traditional district schools with better-performing charter schools.
Similarly, a 2024 report focused on Florida charter schools found strong evidence that charter schools in 12 large and diverse districts improved reading scores (though not math scores) and lowered absenteeism rates of students in traditional district public schools. Finally, a 2024 “gold-standard” lottery study of Massachusetts charter schools found urban charter schools improved student college preparation, enrollment, and graduation.
A Tipping Point?
At what scale do charter schools have these transformative district-wide effects on educational outcomes? A 2024 report, Searching for the Tipping Point: Scaling Up Public School Choice Spurs Citywide Gains, from the Progressive Policy Institute sought to answer that question. (Disclosure: I am a senior advisor at PPI. My colleague Tressa Pankovits is the author of the report. I was not involved in any of the project research.)
This first-of-its-kind analysis examines student math and reading test scores between 2010-2011 and 2022-2023 in grades three to eight in 10 school districts. These districts have more than half of their students eligible for free and reduced lunch; enroll more than 15,000 students; and have at least one-third of their students attending brick-and-mortar charter or charter-like schools.
The analysis shows that low-income students in both public charter schools and traditional district schools across those cities are catching up to statewide student performance levels, typically closing the achievement gap by 25% to 40%. It suggests that a sustained commitment to creating public charter schools by expanding them to enroll at least a third of the district students contributes to improved academic outcomes for all students.
“While one-third is not a guaranteed tipping point, it is true that in every case where charter schools reached or exceeded that scale, academic growth rose across the entire city for all of a city’s low-income students,” the report concludes. “Students in low-income urban communities start catching up with the performance levels of all students statewide, regardless of the type of school they attend.”
Pathways to Opportunity
The PPI analysis cannot determine if charter schools are the only cause of district-wide improvement. For example, state and district policies on accountability or other issues may interact with charter policy to create an environment that produces this result. But cumulatively, these studies suggest that the chartering model based on parent (and teacher) choice, school autonomy, and accountability for results creates a dynamic, virtuous cycle that reduces inequality and has a positive effect on every student and school in a district.
However, there is ample evidence that the charter model of parent (and educator) choice, school autonomy, and accountability for results produces academic, competitive, and social results that lay the foundation for a young person’s pursuit of opportunity. In doing so, successful charter schools reduce inequality and promote equal opportunity for students in both charter and district schools. In that sense, chartering creates a self-improving system of public education. It is a system change because it creates an opening for new school innovations that create incentives for the district sector to change. The result is a dynamic, virtuous cycle for a self-improving system.
In the next piece on charter schools, I’ll describe how charter schools are evaluated and how donors should evaluate them and think about the work they do.
