Student-teacher interactions capture bystanders' attention causing an emotional arousal that takes away the focus of attention form the assigned task. To assess attentional and emotional response to socio-emotional interactions within the classroom, student's eye movement and dilatation were registered while investigating children's environmental sensitivity. Primary school children's pupil response (n = 95) while watching different interaction scenes were registered. Children self-reported on environmental sensitivity. Two mixed-effects regression models for pupil fixation durations and dilatation showed that students' attention was captured more by the teacher yet the focus on the student caused grater arousal. The association between emotional arousal and focus of attention was moderated by students' environmental sensitivity with incongruent socio-emotional exchanges causing grater emotional arousal in highly sensitive children compared to low sensitive ones. Intervention should promote emotionally positive and in-tune teacher-student interactions to avoid students' distraction and sympathetic arousal, especially in more environmentally sensitive students.