"Looping" works: significant test score gains for students assigned to the same teacher for a second time in a higher grade

This study provides new empirical evidence that increased student-teacher familiarity improves academic achievement in elementary school. 

Drawing on rich statewide administrative data, the researchers observe small but significant test score gains for students assigned to the same teacher for a second time in a higher grade. The researchers control for selection into repeat student-teacher matches with teacher fixed effects and either student fixed effects or flexible controls for student past achievement.

 The effects are largest for minorities, and there is some evidence that gains are most evident for students with generally less effective teachers (as measured by value-added). 

There is also suggestive evidence of spillover benefits: students assigned to classes in which a large share of classmates are in repeat student-teacher matches experience gains even if not previously assigned to that teacher themselves. This suggests that effects at least partly operate through improvements in the general classroom learning environment. 

Overall, the findings indicate that there may be potential low-cost gains from the policy of “looping” in which students and teachers progress through early school grades together, and may explain the recent experimental evidence that teacher specialization has negative effects on student achievement given that this likely decreases student-teacher familiarity.