For the purpose of developing a practical support tool for human workers engaged in industrial robot teaching, the activity of teaching operation positions to a robot is analyzed by use of a mechanical explanation model to capture the force-displacement relationship inherent in the work system. The analysis clarifies a basic, normative operation strategy making use of a characteristic frame of reference in the position search space. Based on this finding, a prototype GUI is developed that can provide effective information supports for different granularities of the activity in position teaching. In terms of the distributed information resources model, each element of the GUI is qualitatively investigated to confirm that the proposed GUI represents the activity-related information in a way that affords the robot operators' strategic operations.