A student’s achievement is partially influenced by a teacher other than his or her own, a recent study found.
When an effective teacher joins a grade-level teaching team, students’ learning across the board improves as other teachers in the grade improve. Researchers from the University of Washington, Stanford University, and Vanderbilt University examined teacher “spillover” effects using over a decade of administrative data on math teachers in grades 3 to 8 and their students’ standardized test scores in the Miami school district.
Novice teachers were excluded from the analysis, so the researchers could consider the effectiveness of both incumbent teachers (or those already in the school) and transfer teachers (or those who are new to the school, but had previously taught in the same grade level), based on their previous students’ test scores.
The researchers found strong and consistent evidence of positive spillover effects: If a transfer teacher joins a grade-level team and is one standard deviation more effective than an incumbent teacher, the students in the incumbent teacher’s class will see an increase in their math test scores, the data analysis found.
“Student learning is not a function of just one teacher but of the combined effort of many teachers,” said Min Sun, a professor of the University of Washington College of Education and one of the authors of the report, in a news release.
She said if a student’s teacher has a colleague who is one standard deviation more effective, the student’s chances of going to college would increase by a quarter of a percent after just one year—or, the financial value to the student would be about $10,000 in additional lifetime earnings.
The report found that the opposite effect does not hold true: When an ineffective teacher joins the team, it does not disadvantage the incumbent teachers’ students.
Therefore, mixing teachers with diverse performance levels can increase student achievement, the researchers concluded. If ineffective teachers were paired with more effective colleagues, all students’ learning could be maximized.
In fact, the report suggests such teacher pairings could be more impactful than district-led professional development, which the researchers write has a high price tag and has a null or limited effect on student achievement.
“Teachers often view these district-led professional development programs as lacking close connections with their classroom instruction or failing to help them understand how to improve,” the researchers wrote. “In contrast, the strategic pairing of teachers requires minimal costs, yet generates positive improvements in student achievement.”
A teacher team with different levels of effectiveness would promote on-the-job learning pressure and opportunities, the researchers wrote.
These findings follow a 2009 study that analyzed 11 years of data from North Carolina to first document the spillover effect in teaching. That study looked at both math and reading test-score data for students in grades 3 to 5, and found that student achievement rises across the grade level when a high-quality teacher joins the team.
Researchers have noted that outside of education, the spillover effect in the workforce is widely documented. But many still consider teaching to be a profession where people work mostly in isolation.
The recent study’s authors called for more research to look at the conditions under which these positive spillover effects can be magnified and sustained—for example, how schools can create a systemic structure to promote collaboration.
“School leaders might place more emphasis on strategic professional learning communities to facilitate the diffusion of instructional expertise or structure other opportunities for teachers to share instructional ideas and feedback with each other,” the study said.
More on Spillover Effects and Collaboration:
A version of this news article first appeared in the Teaching Now blog.