The Common Core State Standards represent a sea change in American education policy, but evidence for the standards’ effectiveness has been hard to come by. As I noted last fall, George Washington University’s compendium of over 60 research articles related to the Common Core contained just two papers analyzing its impact on test scores, and the evidence was mixed at best. Even the Common Core’s validation committee acknowledged the lack of evidence behind the movement. “It was pretty clear from the start that nobody thought there was sufficient evidence for any of the standards,” one committee member said.
Now the American Institutes for Research has published a working paper comparing the achievement scores of Kentucky students before and after the state’s transition to Common Core. It’s a careful and comprehensive analysis. To make a long story short, Common Core might be responsible for a small test score gain in the range of 0.01 to 0.04 standard deviations.
The higher end of the range reflects the (questionable) assumption that Common Core’s adoption led to a “preparation effect” – test score gains made after the standards were legally adopted but before they were implemented in the classroom. And if factors aside from Common Core affected test scores — Kentucky made other education-policy changes around the same time — the gains could be even smaller, meaning basically zero.
In the end, the most the study’s authors are willing to conclude is that the transition to Common Core does not seem to have hurt Kentucky students. That’s not an insignificant finding, given the dire predictions made by some opponents. And Common Core supporters can argue that it’s too early to assess the effects of the new standards without allowing for an adequate adjustment period. Quite true. But both points illustrate that the state of knowledge on the standards is not nearly where it should be to justify such a swift and sweeping policy change.