Japanese junior high schools teach technology education by manufacturing activities performed by the students. For instance, an activity could require the application of a specific skill like sawing. It is difficult for the students to evaluate skills objectively by themselves in the manufacturing activities. This paper proposes a mechanism for the students to facilitate the evaluation of their skills within the limited classroom hours. The mechanism evaluates angle and surface roughness of a workpiece by using the sensors of a mobile device. We implemented this mechanism and titled it 'Workpiece Evaluation Support Mechanism for Students'. Additionally, the students confirmed that the mechanism supported the realization of their task in the actual class.