With school returning to something closer to normal after over a year of disruption, most principals are looking for ways to get students back on track. Recent research suggests surprising benefits to student outcomes from a relatively straightforward policy: keeping teachers in their current grade and subject assignment to the extent possible.
Teachers, just like students, learn by doing, and those teaching 5th grade for the second time will most likely be better at teaching that grade than they were the first time. Switching them to a new grade loses the benefit of that learning.
Moreover, teachers new to a grade level can disrupt the existing team. Grade-level teacher teams learn to work together. Put a new person on the team, and the team has to relearn its collaboration routines. Plus, veteran teachers will turn some of their focus from their classroom to helping their new team member.
To be clear, the evidence suggests gains from keeping teachers in their current grade will be small. Using data from New York City, Susanna and colleagues found that switching grade or both subject matter and grade is associated with a 1 percentile to 2 percentile decrement in student-achievement outcomes the following year. This magnitude is about one-third as large as having a teacher new to teaching.
The story is similar in data from a large urban district in California, with the negative effects of grade-switching particularly apparent in teachers who move more than one grade level. Grade-switching in the California data also predicts teachers’ exit from their school.
Even though the gains from stability aren’t large, they are easy to achieve because reducing churn would require no costly teacher professional development or teacher time out of the classroom. Further, grade-level churn is so prevalent in schools that even relatively small gains add up. In New York City and California, respectively, 19 percent and 17 percent of teachers switched to a new grade within their school each year. In New York City, over half the studied teachers switched assignments within their first four years of teaching. Switch rates appear somewhat lower in New York state data but are still substantial, at roughly 15 percent of teachers switching teaching assignments within their school every year.
Of course, teaching assignments are not always under the principal’s control. Teacher-position vacancies, larger or smaller cohorts of students across years, and teachers who wish to move to a grade they deem more desirable or to challenge themselves with something new can all lead to grade-level changes.
Anecdotally, however, we have heard stories of principals who see grade-switching as a way to “shake up” their teaching staff. And sometimes one required grade change leads to many other changes. A 2nd grade teacher leaves, making a hole to be filled. A new teacher could fill that hole, or a 3rd grade teacher could move to 2nd grade, leaving a hole in 3rd, which is filled by a 4th grade teacher, and the new teacher moves into 4th. Three grade changes occur when only one was required. Thus, principal discretion does seem to play a role in some grade-level churn.
Some principals may make grade switches in hopes of achieving a better match between a teacher and the knowledge and skills needed to provide instruction in a particular grade. Work by University of Maryland researcher David Blazar, for example, provides some suggestive evidence that principals may be switching lower-performing teachers, perhaps in an attempt to improve their performance. In these cases, any decrements to student achievement from the switching would be temporary, with better performance in the ensuing years within that grade.
Even though the gains from keeping teachers in their existing grade levels aren’t large, they are easy to achieve.
However, while both New York City and California teachers appear to recover to their preexisting effectiveness within a year or two of the move, in neither data set do grade switches appear to foster better student performance in subsequent years. On average, even if principals are moving teachers in an attempt at improvement, churning is not helping in the long run, and it is hurting in the short run.
Finally, grade-switching more often affects historically marginalized student populations: In both the New York City and California data sets, there is evidence that these students, as well as all students in low-performing schools, are more often assigned to teachers who have recently switched teaching assignments.
Why do grade switches negatively impact student performance? We have surprisingly little direct evidence about this topic. But we do know that new teachers quickly improve in their ability to raise student-test scores over the first several years of their careers, likely because their teaching-specific knowledge and skills improve. The effectiveness penalty paid by grade switchers may similarly reflect not having the best knowledge and skills for their new grade. A specific example is the use of curriculum materials. Teachers may use them more efficiently and effectively the second or third time through them. They might, for instance, add features to enhance student interest or to help students practice prerequisite skills.
Another hint about why grade-switching can harm student performance comes from studies that examine what happens when teacher movement breaks up grade-level teams. Research from both Ebony Bridwell-Mitchell of the Harvard Graduate School of Education and James P. Spillane of Northwestern University suggests that grade-switching disrupts within-school social ties; these social ties are thought to assist teachers in implementing new approaches to instruction and improving student achievement.
Similiarly, work by University of Michigan researcher Matthew Ronfeldt with others found that better-quality teacher collaboration in instructional teams is related to greater student performance gains. Collaboration, like social ties, can take a hit from team turnover.
This all said, it is still better to switch teachers to a new grade as opposed to losing them to another school and then replacing them with a brand-new teacher. But principals could make change at the margin to keep teachers in grade. When choosing between two teachers to fill a vacancy, for instance, principals could choose the teacher with experience at that grade. Principals can also discourage some grade-switching by requiring teachers to apply for the change or to interview with the grade-level team they want to join. Finally, when grade-switching does occur, principals can encourage mentorship of new-to-grade teachers by those who remained in grade and know the students and material the best.
