Does Diagnostic Math Testing Improve Student Learning

California, like all other states, has adopted a sweeping school accountability system that features annual testing of students. The main state test, the California Standards Test (CST), serves multiple goals, the foremost of which is to measure student proficiency and to determine whether schools receive interventions and sanctions set out in the federal No Child Left Behind law. There is another type of test, freely available to middle and high school math teachers throughout California, which holds two key advantages over the CST math tests. The Mathematics Diagnostic Testing Project (MDTP) offers course-specific assessments that provide teachers with timely feedback on their students’ strengths and weaknesses in mathematics, often returning feedback to teachers on individual students and the entire class within a week of testing. In this way, teachers can quickly act on what they learn about their students ’ mathematics skills. A second advantage of the MDTP tests is that they provide more detailed feedback about each student’s areas of strength and weakness than do the CST mathematics tests. The MDTP attempts to “diagnose”, not just “report.” This study examines the effect of MDTP testing on students ’ mathematics achievement, using detailed student-level data from the San Diego Unified School District (SDUSD), the second largest district in California. The MDTP has in fact been used in two ways in the district. First, many math teachers have