In recent years, educational-support robots, which are designed to aid in learning, have received significant attention. However, learners tend to lose interest in these robots over time. To solve this problem, researchers studying human-robot interactions have developed models of emotional expression by which robots autonomously express emotions. We hypothesize that if an educational-support robot uses an emotion-expression model alone and expresses emotions without considering the learner, then the problem of losing interest in the robot will arise once again. To facilitate collaborative learning with a robot, it may be effective to program the robot to sympathize with the learner and express the same emotions as them. In this study, we propose a sympathy-expression method for use in educational-support robots to enable them to sympathize with learners. Further, the effects of the proposed sympathy-expression method on collaborative learning among junior high school students and robots are investigated.