This paper reports on a joint research project in which a researcher in applied linguistics and elementary school teachers in Japan revealed the role of teacher-student relationships in English as a foreign language (EFL) education. Based on previous research that movement synchrony between children and adults is necessary in acquiring the first language, the experiment was conducted using shadowing practice in a teacher-training course. The results proved that the teachers moved their body most when they had close relationships with a model reader. This study succeeded in convincing the teachers of the importance of synchrony in an EFL class and daily classroom interaction in elementary school.