A new study provides some of the first evidence to document a “spillover effect” in teaching, noting that teachers raise their games when the quality of their colleagues improves. Studies outside of education have long shown that effective workers can have a spillover effect on their colleagues. But up until now, studies have not noted the same pattern in teaching, the long-held belief being that teachers work mostly in isolation.
C. Kirabo Jackson and Elias Bruegemann, the authors of “Teaching Students and Teaching Each Other: The Importance of Peer Learning for Teachers” published in the American Economic Journal: Applied Economics, based their findings on an analysis of 11 years of data on North Carolina schoolchildren. They focused on math and reading test-score data for students in 3rd through 5th grades. They measured teacher quality by tracking what they referred to as “observable” characteristics, such as years of experience and certification, and by calculating how effective teachers were at raising the test scores of their students.
The researchers found that student achievement rises across a grade when a high-quality teacher comes on board. Their analysis showed that for the average educator teaching in a grade with three other teachers, replacing one peer with a more effective one has a spillover effect of .86 percent of a standard deviation on students’ test scores. “The effects are big enough that they would matter,” stated Jonah Rockoff, an outside labor economics expert and assistant professor at Columbia University. “If we think about rewarding teachers based on student outcomes, teachers are going to care about who’s teaching alongside of them.”
Jackson and Bruegeman argue that the student test scores rise because teachers are learning from their new colleagues and not because the new teacher’s arrival is motivating peers to do better or because that teacher is helping out other teachers by doing some of the teaching. Their argument is based on the finding that the effects persist over time. The study also found that good teachers seem to have the most impact on beginning teachers.
The idea that teachers, particularly beginners, are learning from more effective colleagues on an informal basis could explain why several recent studies have found that formal teacher-induction programs don’t seem to be very effective.
The authors and some independent experts said the new peer-effects findings are important because they raise questions about the way schools are staffed and carry implications for school staffing practices and debates going on now at the national and state levels over how to structure merit-pay plans for teachers. Even though this is the most compelling evidence to date that the spillover effect exists among teachers, experts also agree that more research is needed to figure out exactly how peer effects work within the teaching profession.
—“Teaching Students and Teaching Each Other: The Importance of Peer Learning for Teachers,” by C. Kirabo Jackson and Elias Bruegemann, American Economic Journal: Applied Economics, Oct. 2009.
