Critics of using student test scores to evaluate teachers often point to research that shows there is a limitation to using student test scores to evaluate teachers. Due to such limitations, critics argue, student test scores shouldn’t be used to evaluate teachers. Critics typically go on to argue, if teachers are to be evaluated they should be evaluated based on how well they teach by conducting classroom observations. The problem, however, is this argument is based on the assumption that classroom observations are a more accurate measure of a teacher’s true effectiveness.
To this end, researchers at the American Institutes of Research (AIR) recently attempted to determine how accurate classroom observations were at measuring a teacher’s effectiveness. What they found is contrary to popular belief. In fact, classroom observations are not better at evaluating teacher effectiveness than using student test scores—when used within quality value-added models.
Now, this doesn’t mean classroom observations shouldn’t be used to evaluate teachers. In fact, it is critical, as they not only provide information on the quality of a teacher’s instruction but they also provide valuable feedback to teachers about the strengths and weaknesses of their instructional practices which test score can’t provide. However, it is not only important to measure how well a teacher teaches, it is just as important to determine what impact they have on their students as well. Just as in baseball, a player may have the most technically sound swing but if he can’t hit the ball they’re not going to remain on the team for very long.
This is why teachers must and are being evaluated on multiple measures, not just test scores or classroom observations. As I laid out in Building a Better Evaluation System, to accurately evaluate the effectiveness of teachers their evaluation should be based on multiple measures such as student test scores, classroom observations or other measures. No single measure, whether classroom observations or test scores, can possibly provide a full and accurate picture of the quality of the instruction a teacher provides. By incorporating multiple measures into a comprehensive teacher evaluation program, districts can not only evaluate the quality of teachers, but more importantly identify those areas where teachers can improve.
While neither test scores nor classroom observations are perfect measures of teacher quality when used in isolation, when combined they work together to provide a valuable tool in evaluating and supporting our nation’s teachers. – Jim Hull