New study on charter schools in Boston

"Informing the Debate," is a new study that finds that charter schools in Boston are more effective in raising student achievement than traditional Boston public schools. The methodology used is well-accepted: comparing the achievement levels of the students who "win" the lottery and are able attend a charter school compared to those who "lose" and remain in regular public schools.

As Eduwonkette points out, only one quarter of Boston charter schools were analyzed -- oversubscribed schools with a waiting list, so the results of these schools may not be typical.

Nevertheless, this looks to me a good study, though it doesn't begin to analyze why these particular charter schools are more successful in raising student achievement. There are two possibilities that come to mind, and both may be true.

1- Class Size -- an examination of the descriptions of a random selection of the charter schools included in the study, either from reports by the Massachusetts state education dept. or self-reported by the school itself, shows that classes tend to be much smaller in these schools than in the regular BPS system, and in some schools, as small as 15 (as in the Boston Collegiate Charter School). In most, classes are about 18-22 students; while the regular BPS system has class sizes ranging from 25-28. In fact, many of the charter schools studied openly proclaim that their small classes are critical to their success. In general, it is easier for charter schools to reduce class size because they are able to cap enrollment, unlike traditional public schools.

2- Peer effects. Though the study finds that the randomly selected students who attend charter schools do better than those who remained in the BPS system, it also states that "Charter Schools ... serve a smaller proportion of special education students, free- and reduced-price lunch students, and English learners than do the traditional BPS schools. In addition, high school Charter students tend to come in with substantially better math and ELA performance on the MCAS..."

So to the degree that the "winners" of the lottery would tend to surrounded by higher performing and more advantaged students, this in itself could boost their achievement levels.

Tom Kane , one of the authors of this study, has been quoted as saying that "The next step is to identify what's working in charter schools that can be transferred back into the traditional public schools to improve student achievement." Let's hope they manage to achieve this. I am aware of few such studies that have honestly attempted to do this in the past.