According to recent studies, the existence of previous knowledge has been found to be involved in more advanced knowledge acquisition in the human study. Further, when the body motion synchronized, empathy for others has also been found to be important key of interaction. In this study, we focus on those points, by looking at whether the psychological state and body motion are affected by the prior knowledge, and of evaluating the internal understanding and consent of knowledge understanding from the body synchrony will consider the possibility. Specifically, we conducted the experiment lecturer task on teacher-student interaction. There are two group conditions. One is given prior knowledge, the other is not given prior knowledge. The students of the two groups are given same lecture. psychological state is measured using a questionnaire, physical motion is measured using an acceleration sensors. The results reveal that in prior knowledge group, the psychological synchrony is likely to occur more than no prior knowledge group and the body synchrony is found to occur at an early stage with closer to 0 time lag. These differences are occurred due to the involvement of the lecture. The students with prior knowledge is more likely to be involved in the lecture more than the students with no prior knowledge.