Sep 2 2016
White Center Heights classroom

Effective teachers don't just impact their own students' achievement, they help improve the performance of their fellow teachers' students. New research by Min Sun of University of Washington College of Education and her collaborators points toward how schools can maximize the talents of their teachers to improve instruction, especially poverty-impacted and minority children who often are taught by less experienced teachers.

The positive spillover effect of effective teachers was quantified by Sun and her colleagues in their paper "Building Teacher Teams: Evidence of positive spillovers from more effective colleagues," newly published in the journal Educational Evaluation and Policy Analysis.

"Student learning is not a function of just one teacher but of the combined effort of many teachers," Sun said, and introducing more effective peers into a teacher group helps drive improvement for all students. “This implies a paradigm shift from practices that primarily promote individual performance, which has dominated federal and state policies in the past couple of years—particularly as in Race To The Top and No Child Left Behind waivers.”

Sun and her colleagues looked at more than a decade of data covering math teachers in grades 3 to 8 who can be linked to their students' standardized test scores in the Miami-Dade County Public Schools. They found that if a student has a new peer teacher at the same grade level who is approximately one standard deviation more effective than his or her own teacher, that student would have a 1.9 to 2.8 percent of a standard deviation increase in math test scores. This spillover effect is 23 to 29 percent of the student’s own teacher’s effect on his or her achievement gains.

Moreover, the research team found that spillover effects are asymmetrical.

"Although teachers benefit from a relatively effective peer, their students are not meaningfully disadvantaged by the presence of relatively ineffective peer," Sun said.

Sun believes the study's findings could help states and local school districts respond to the U.S. Department of Education's 2014 call—as well as discussion on staffing effective teachers for all students in the Every Student Succeeds Act—for them to develop strategies to increase the equitable distribution of teacher quality across schools.

"There is a broad consensus about the need to have high-quality teachers for all students, especially underserved learners," Sun said. "We believe this work sheds light on some promises of the design of teacher incentives or assignment programs to magnify effective teachers’ contribution to the whole teacher team’s performance."

Sun said the new study suggests one promising strategy for building teaching teams able to maximize all students' learning is to pair ineffective teachers with more effective colleagues. While a recent report from The New Teacher Project found school districts spend an average of $18,000 on district-led professional develop per teacher each year, most studies of teacher professional development show no or limited positive effects on student achievement.

“In contrast to these costly district-led professional development programs that lack close connections with classroom instruction or fail to help teachers learn how to improve instruction, strategic grouping of teachers seems a more cost-effective way to promote teacher learning,” Sun said. “Principals can group teachers with diverse performance into teams. This strategic grouping promotes on-the-job learning pressure and opportunities for teachers, which leads to improvement in student learning.”

District and school leaders, Sun said, should think about how to make structural changes, such as coherent curriculum and common planning times or incentive mechanisms, to enhance collaboration and spillover among teachers.

“We hope that our findings change policymakers and school leaders’ theory of actions in managing the teacher workforce,” Sun said. “The locus of these policies should not be only at the individual teacher level; rather, targeting teacher team building may be a fruitful strategy to bring out systemic improvement.”


Min Sun, Assistant Professor of Education

Dustin Wunderlich, Director for Marketing and Communications