Proponents of charter expansion point to a large body of research showing that Boston charter schools produce large achievement gains for their students.
Along with the CREDO report, multiple other studies have found significant test score bumps for students who attend Boston charter schools. One study compared students who won the right to attend a charter to those who applied but lost, finding charter attendees had significantly higher test scores across different exams, including the SAT, and were more likely to attend four-year colleges.
However, charter students had lower on-time high school graduation rates, which one of the researchers, Sarah Cohodes of Columbia University Teachers College, said likely results from a more rigorous curriculum in charter high schools.
Although it is true that Boston charters serve slightly fewer special education students and significantly fewer English-language learners than district schools, the research ensures apples-to-apples comparisons because of the schools’ enrollment lotteries. The researchers also tested whether a “peer effect” of being surrounded by more motivated students might explain this success and found it unlikely.
Another study looked at Boston district schools taken over by charters; again, fairly large achievement gains were found.
Richard Stutman, president of the Boston Teachers Union, explained in an interview that he didn’t question charters’ test score gains, but said, “They’re teaching to a standardized test. No one is arguing that the kids who [attend charters] are [more] well-rounded.”
A separate study conducted by Cohodes of Columbia found no evidence to support the teaching-to-the-test theory. Although her analysis can’t be conclusive, Cohodes examined whether charters were stressing questions most likely to show up on state tests and higher-stakes subjects like math and English.