Teacher and classroom context effects on student achievement: Implications for teacher evaluation

The Tennessee Value-Added Assessment System (TVAAS) has been designed to use statistical mixed-model methodologies to conduct multivariate, longitudinal analyses of student achievement to make estimates of school, class size, teacher, and other effects. This study examined the relative magnitude of teacher effects on student achievement while simultaneously considering the in¯uences of intraclassroom heterogeneity, student achievement level, and class size on academic growth. The results show that teacher effects are dominant factors affecting student academic gain and that the classroom context variables of heterogeneity among students and class sizes have relatively little in¯uence on academic gain. Thus, a major conclusion is that teachers make a difference. Implications of the ®ndings for teacher evaluation and future research are discussed. Overview Over the years, educational researchers have investigated many factors considered to affect student learning. At the heart of this line of inquiry is the core belief that teachers make a difference. There are continuing debates about how much the extant teacher-effectiveness literature (e.g., Brophy, 1986; Porter & Brophy, 1988) can be trusted to identify characteristics of effective teachers, and additional debates as well about how such research ®ndings should frame the subsequent development of teacher evaluatio