Licensure tests: depending on who you ask, they're either an important check on a prospective teacher's knowledge before entering the profession or a burdensome requirement that keeps good candidates out of the classroom. A new study from CALDER researchers Dan Goldhaber, Trevor Gratz, and Roddy Theobald takes a look at the validity of a battery of tests taken by aspiring Washington state teachers.

The researchers studied the relationship between two kinds of licensing tests used in the state and student performance. Specifically, they examined the basic skills test that almost every Washington teacher must take in order to gain admission to a teacher preparation program and subject matter tests, limited in this study to teachers taking secondary math and biology tests.

The findings were mixed. The state's basic skills test served as a "modest" predictor of student outcomes in math and ninth-grade biology. So, too, was the biology test quite predictive. However, the math test was not particularly effective in predicting student performance.

What could explain a result that says subject matter knowledge in biology does matter but math does not?

Author Dan Goldhaber offers this insight: "The short answer is that we really don't fully understand these different results because there is so little evidence to date about what predicts the effectiveness of science teachers. A bit of speculation, however. It is important to remember here that we did find a relationship in math, just not as strong a one as might have been expected. After all, teachers who did better on the basic skills test—which includes math—were more effective. It would not surprise me if the math subject tests would have turned out to be more predictive for later high school math courses, such as calculus, where a teacher's specific content knowledge of calculus is without question important."

To that point, we were surprised to read that this study was enough for at least one education advocacy group, MarylandCAN, to issue a call for the end to meaningless licensing tests—in our view, a hair's breadth away from asserting that teacher's subject matter knowledge doesn't really matter. A slippery slope, indeed.