Do classroom teachers matter for academic achievement of students? Evidence from random assignment of students to teachers in China

In China’s middle schools, each class is assigned both subject teachers who only instruct students on specific course and one classroom teacher who not only teaches in class but also provides out-class-support. This study evaluates whether classroom teachers are more effective than subject teachers in improving students’ academic performance. To examine the causal effect of the classroom teacher, I take the advantage of data that students are randomly assigned to classes in middle schools in China and exploit the within-teacher variation given a teacher acting as a classroom teacher for his or her own class but also giving lectures to other class(es) as a subject teacher in one term in China. The findings show that a classroom teacher has a significant positive effect on the students’ test scores in his or her own class compared with other classes he or she teaches. I further investigate the possible mechanisms and find that classroom teachers tend to have more interactions with their own class both inside class and outside class beyond giving lectures than with other classes they teach. This study provides insights for understanding the effect of teacher support outside class on students’ academic outcomes.