Teacher turnover has a significant and negative effect on student achievement in both math and English/Language Arts. That is the finding of a research team led by Matthew Ronfeldt of the University of Michigan in their recently released study, How Teacher Turnover Harms Student Achievement. Two weeks ago, I wrote here about recent research connecting principal leadership to student achievement and the effects of quality leadership on teacher turnover. The study by Ronfeldt and his colleagues presents compelling evidence for connections between disruption in a school’s faculty and lower achievement levels. Schools serving high numbers of low income and African American students experience disproportionately negative effects from high rates of turnover.

Ronfeldt and colleagues estimate the effects of teacher turnover on more than 850,000 4th and 5th grade students in New York City over eight years. The research team addresses previous work indicating turnover may improve achievement as a result of improved quality of instructors in a school. The principal leadership study, in fact, mentions relatively high rates of turnover in schools with good principals as a result of their efforts to exit teachers with poor performance ratings and replace them with higher performing instructors. As that team noted, however, “the benefits of reducing turnover clearly depend on both the composition of entering and exiting teachers and the transition rate.” The present study tackles the question of whether turnover on its own significantly decreases levels of student achievement.

The study’s findings include:

  • Teacher turnover has a significant and negative impact on student achievement in both math and English/Language Arts
  • This negative impact is particularly harmful in schools serving large proportions of low-performing and African American students
  • Students of teachers who remain in schools perform significantly worse when rates of turnover increase, and negative effects are mostly found in lower performing schools
  • Although changes in teacher quality that result from turnover may have some effect on student achievement, turnover in and of itself likely has some negative effect for students

These findings may come as little surprise to educators who have worked in schools with high rates of turnover. The findings held true for schools regardless of their age or the size of their student populations. Ronfeldt and colleagues also found ongoing school reform efforts in New York City “are not driving the negative effects of turnover” they describe. Rather, a compelling possible explanation for this effect “is that turnover negatively affects collegiality or relational trust among faculty; or perhaps turnover results in loss of institutional knowledge among faculty that is critical for supporting student learning.”

If a school’s leaders are continuously spending time and other resources to recruit teachers only to pass through a revolving door, they have that much less time and fewer resources to spend on pursuing the school’s mission of improvement. Teachers who remain in schools with high turnover rates receive fewer opportunities to receive needed professional development and to develop essential relationships with their colleagues in support of student achievement. The diminished levels of trust and institutional culture resulting from high rates of turnover inhibit the ability of a principal and his or her colleagues to build an effective learning community.

Tennessee is a long way from New York City in many ways, but the success of our state’s ongoing reform initiatives will depend on building a stable professional population of highly effective, well supported teachers. Some turnover is natural and needed to enhance the professional quality of Tennessee’s teachers. But we also must be attentive from a policy standpoint to provide support and incentives for great teachers to remain in their schools, especially in schools with large proportions of students from historically underserved populations. This approach will help stop the revolving door of teachers in these schools and provide a high quality, equitable education for all of Tennessee’s students.