It’s the start of another school year, and parents everywhere are asking themselves: Is my child’s teacher any good? The Los Angeles Times recently attempted to answer that question for parents. Using a statistical technique known as “value added”–which estimates the contribution that a teacher made to a student’s test-score gains from the beginning to the end of the school year–the paper analyzed the influence of third-, fourth-, and fifth-grade teachers on the math and reading scores of students in the Los Angeles Unified School District. The results suggest a wide variation in the quality of L.A.’s teachers. The paper promises a series of stories on this issue over the next several months.
The Times has admirably highlighted the importance of using data to evaluate teacher performance, confirming the findings of a wide and growing body of research. Studies show that the difference between a student’s being assigned to a good or bad teacher can mean as much as a grade level’s worth of learning over the course of a school year. While parents probably don’t need studies to tell them who the best teachers are–such information is an open secret in most public schools–academic research helps underscore the inadequacy of the methods currently used to evaluate teacher performance. Even the nation’s lowest-performing school districts routinely rate more than 95 percent of their teachers as satisfactory or higher.