To reduce the cost to develop service robot applications, we have been developing PRINTEPS, an AI and service robot application development platform for end users. PRINTEPS provides a scenario editor to describe the workflows for robots’ actions and human-robot interactions. The scenario editor enables the developer to create workflows while reusing the entire workflows or individual operation processes; however, since end users such as domain experts usually do not know functions and properties of robots, it is difficult to identify and modify the reusable parts to suit the purposes of reuse when reusing the entire workflows. In contrast, it is also difficult to work out different combinations of operation processes when reusing the individual operation processes. To solve these issues, this study proposes a teaching assistant (TA) robot design tool based on knowledge chunks reuse. Two public elementary school teachers created workflows for TA robots using the proposed tool, and each teacher conducted a lesson with TA robots once. Through questionnaires given to the teachers and pupils, the proposed tool and TA robots were evaluated to confirm their usefulness.