Long-time followers of skoolboy (hi, Mom!) know that his first posts on eduwonkette’s blog were about class size. I argued for championing class size reduction as the right thing to do for children and for teachers—an argument grounded in the moral content of public schooling more so than in the technical consequences of class size reduction for standardized test scores.
Over the past year, I’ve observed a number of trends in the operation of big-city school districts. I’ll use New York City as my key example, because it’s my hometown, but the issues are sufficiently general to warrant posting here.
First, large districts are increasingly trying out innovative policies and practices for which there is little or no pre-existing research support. In New York City, the issuing of school report cards and conduct of school quality reviews are high-stakes evaluative practices for which there’s no prior evidence showing beneficial outcomes. In Washington, DC and New York City, school officials are offering incentives in the form of cash and cellphones to students in exchange for meeting academic performance targets. Some of these innovations have evaluations built into their design, whereas others do not.
Second, the arguments in support of these innovations often rely on claims that other innovations have not been successful. The best example is the juxtaposition of teacher quality and class size reduction. All kinds of policies regarding teachers—value-added assessment, merit pay, new recruitment strategies—are being justified on the grounds that teacher quality has much larger consequences for student achievement (read: test scores) than other policy choices, such as class size reduction.
Third, a lot of the claims about these effects take the form of “Research shows…”, which eduwonkette has derided as glib and poorly documented. There are, of course, important studies of both teacher quality effects and class size effects on student outcomes, but different studies yield different estimates of the magnitude of these effects. In part, this is because the impact of a particular innovative policy or practice is contingent on how the policy or practice is implemented and the features of the local organizational and institutional context for the new intervention. (We might expect, for example, that class size reduction would have different effects in classrooms with novice teachers than in classrooms with experienced teachers, or in classes that differ in the amount of prior student misbehavior.)
So when a policymaker confidently says that we should prefer innovations designed to influence teacher quality rather than class size reduction in a particular local setting—say, New York City—what’s the evidence for such a claim? Specifically, what does research tell us about the consequences of a well-designed class size reduction intervention in New York City?
The answer is, we don’t know—because there has never been a carefully-controlled study of class size reduction in New York City.
So at this point, skoolboy throws down the gauntlet: If we’re serious about data-driven decision-making, we should put our money where our mouth is, and demonstrate the relative effectiveness of class-size reduction and other policy initiatives. I call on the New York City Department of Education to carry out a well-designed study—ideally, a randomized experiment—of class size reduction in New York City public schools. View it as a small-scale pilot, as is true for some of the other initiatives, such as the student incentive plans, and look for some private funding (if it’s not feasible to draw on the operating budget). It will not be hard to pull together some of the leading researchers on class size to inform the design (and it wouldn’t kill anybody to have a couple of knowledgeable parents and teachers at the table too.) There’s nearly a full year to get this off the ground for the start of the 2009-10 school year.
skoolboy is willing to live with the findings of a well-designed and well-implemented study of class size reduction in New York City, whether they support or refute claims about the efficacy of class size reduction. What I cannot support are claims that “research shows” that teacher quality is more important than class size reduction for student outcomes in New York City—or any other local education setting—in the absence of research that actually does show this.