National Achievement Data Show Charter Schools Have Positive Impact

Issue Brief

Parents, teachers, and other school reformers who want to make full use of public charter schools to help students who are struggling in regular public schools can take heart from a new national study by eminent Harvard University education researcher Caroline Hoxby. The study found that, nationwide, students in established charter schools score significantly higher on state reading and mathematics examinations than do their peers in conventional public schools.

The study, “Achievement in Charter Schools and Regular Public Schools in the United States: Understanding the Differences,” is the most comprehensive look yet at the effect of charter schools on student achievement. It examines data for 99 percent of all elementary pupils in charter schools across the nation.

Charter schools are publicly funded schools that receive leeway to innovate in such areas as curriculum, management, or use of technology in exchange for a contractual pledge to deliver tangible results.

By contrast, The New York Times gave front-page coverage last summer to a study by the American Federation of Teachers (AFT) that relied on data from a mere 3 percent sample of charter-school fourth-graders drawn by the National Assessment of Educational Progress. Because charters enroll only 1.5 percent of all K-12 students, it is statistically important to include almost all of them in any valid study, Hoxby noted.

The AFT (the leaders of which oppose the very existence of charter schools) claimed that its data showed charter students scored lower than their peers in regular public schools. However, their report failed to take into account the fact that charter schools serve a much higher proportion of children from low-income and minority homes than do public schools in general.

The Harvard study matches each charter school to the closest neighborhood public school (or the one with the most similar racial composition if there are more than one). That was a logical step because elementary pupils typically travel the shortest distance possible to school.

Among the findings:

Compared to students in the matched regular public school, charter students overall are 5.2 percent more likely to be proficient in reading and 3.2 percent more likely to be proficient in math.

Students in charters that have been in operation longer are more likely to have an advantage over their peers in conventional public schools. The progression goes like this: In reading the edge is 2.5 percent for a charter school that has been up and running 1 to 4 years, 5.2 percent for a charter operating 5 to 8 years, and 10.1 percent for a charter school operating 9 to 11 years. Hoxby observed that it is common for charter schools to improve substantially each year they are in operation. She also noted that low-performing charter schools often fail to attract many students and usually exit quickly.

While charters tend to spring up in areas where many students are disadvantaged and families have scant ability to exit troubled schools, charters with a high proportion of poor or Hispanic students do indeed show an extra advantage in their students’ test scores.

While the findings present strong evidence of academic results, charter schools have demonstrated other advantages as well. In his important new book, Creating the Capacity for Change, Minnesota school reformer Ted Kolderie explains the need for taking a broad perspective in measuring the success of innovative schools.

“New and different schools will require new kinds of assessment,” Kolderie argues. “It will be important to look with fresh eyes for what is working well in these schools. It may not be high scores. It may be gain on scores. Or it may be better attitudes, better attendance, more student initiative, greater curiosity about learning. Academics are important but not all-important. Safety is important. A healthy school culture is important. Empowerment is important. The public wants many things from its schools.”