The Scylla and Charybdis in this discussion of teacher evaluation are standardized achievement test data on the one hand, and classroom observational systems on the other. These are the two most common methods used to judge teachers' competency. Both have serious flaws: the former primarily with validity, the latter primarily with reliability. At…

Background: There has been rapid growth in value-added assessment of teachers to meet the widely supported policy goal of identifying the most effective and the most ineffective teachers in a school system. The former group is to be rewarded while the latter group is to be helped or fired for their poor performance. But, value-added approaches to…

In the United States, but not only here, the movement to evaluate teachers based on student test scores has received powerful political and parental support. The logic is simple. From one testing occasion to another students should show growth in their knowledge and skill. Similar types of students should show similar patterns of growth. Those…