This new study examines the impact of math textbooks on student achievement in California; it was authored by Cory Koedel and Morgan Polikoff, two alumni of Fordham’s and AEI’s Emerging Education Policy Scholars program.
They identified 240 unique textbooks across roughly 7,800 schools serving K–8 as of 2012–13, and selected a final sample of 1,878 schools that utilized one of four particularly popular books used in California from 2008–13 (with most entering use in the fall of 2008 or 2009). The books are enVisionMATH California, California Math, California Mathematics: Concepts, Skills, and Problem Solving, and California HSP Math. They merge curriculum adoption data with various school and district characteristics, census data (such as median household income), and achievement data (school average test scores on state math tests). Koedel and Polikoff selected the books for study because, among other criteria, they were adopted in enough schools serving K–8 to enable the requisite statistical power to evaluate them.
Most of the results are based on third-grade achievement with some evidence on grades four and five. The authors use multiple analytic techniques that match schools based on pre-adoption characteristics (size, student demographics, and prior achievement) and track achievement up to four years.
The key finding is that, compared to the other three textbooks, California Math (published by Houghton Mifflin) has a positive impact evident in the first year after adoption that persists through year four of adoption. The effect is in the range of .05 to .08 standard deviations, depending on the year and the analytic model.
This study contributes to a small but increasingly persuasive body of research suggesting that choice of curriculum matters. These type of studies are, however, hard to do because most states don’t collect data on curricular materials, and if they do, they are spotty and/or not coded consistently. It therefore takes a long time to clean the data if one is lucky enough to have them. Case in point: California Math is no longer sold in California—or apparently anywhere else. The same can be said for two of the other three texts.
This is not the first study to kvetch about the scarcity of data on curricular materials. But it stings harder when the analysts describe the effects as “on par with what one could expect from a hypothetical policy that substantially increases the quality of the teaching workforce” at “extremely low cost,” since choosing one textbook over another is a “straightforward policy option for raising student achievement.” Eesh.
SOURCE: Cory Koedel and Morgan Polikoff, “Big bang for just a few bucks: The impact of math textbooks in California,” The Brookings Institution (January 2017).
