A recent article by the National Center for Analysis of Longitudinal Data in Education Research (CALDER) investigates whether STEM teacher candidates who score better on licensure tests are also more effective at improving student performance once they enter the teaching workforce. After replicating earlier findings that teacher basic-skills licensure test scores are a modest and statistically-significant predictor of student math test score gains in elementary grades, researchers focused on three subject/grade combinations—middle school math, 9th grade algebra and geometry, and 9th grade biology—in which both current and prior year subject-area test scores were available and estimated value-added models that provided within-subject estimates of the relationship between teacher licensure test scores and student achievement gains.
The study concludes that basic skills tests are modestly predictive of student achievement in middle and high school math and highly predictive of student achievement in high school biology. On the other hand, subject-specific tests are a statistically-significant predictor of student achievement only in high school biology. In fact, the study states: Teacher content knowledge (as measured by credential tests) is simply more important to student performance in science than in math and is worth future study.
To read the full report, see http://www.caldercenter.org/sites/default/files/WP158.pdf