In the last few years, a number of large-scale studies of teaching have elucidated how teacher quality makes a difference in the achievement of students. Three of these studies and their conclusions are summarized below. An examination of studies that focus more specifically on science and mathematics teaching and K-12 student achievement follows.
Later reports frequently cite studies by Sanders and colleagues (see below), Ferguson (1991), and Ferguson and Ladd (1996) as evidence that the qualifications of teachers not only matter in student achievement but also are major variables in improving student learning and achievement.
For over 15 years, Sanders and his colleagues associated with the Tennessee Value-Added Assessment System (TVAAS) have analyzed data from annual tests in mathematics, science, reading, language, and social studies given to grade 3-8 students in Tennessee. Utilizing a database now in excess of 5 million records, Sanders and his colleagues have tracked individual students over time and studied each child’s academic achievement year by year. In this way, they have been able to identify a year when a child makes average progress, exceeds average progress, or achieves no gain.
In a study intended to gauge the cumulative and residual effects of teacher qualifications on student achievement, Sanders and Rivers (1996) gathered test or achievement data for a cohort of students from the time they were second-graders to the time they had completed fifth grade. By disaggregating the data, the researchers were able to see the impact of quality teaching on each child over time (Sanders and Rivers, 1996).1 Sanders and Rivers reported that student achievement at each grade level correlated positively with the quality of the teachers who taught those students. Also of interest was the researchers’ discovery of residual effects; that is, they found that the individual children they studied tended not to recover after a school
Sanders, Rivers, and their colleagues did not define teacher quality a priori. Rather they sought to identify “quality” teachers based on how well students achieved in one year of school. Using the Tennessee achievement tests as a measure, they determined if the students in a given teacher’s class achieved a normal year of growth in various subject matter fields such as mathematics or more or less than a normal year’s academic growth. Using these criteria, they then identified teachers as “below average quality,” “average quality,” or “above average quality.”