This paper explores the possible advantages of substituting teachable agents in a learning environment, with a humanoid robot as the non-human tutee. Teachable agents are used as an extension to educational games in order to leverage engagement, reflection and learning. The learning environment is engaging and shown to be effective for learning and promote self-efficacy in experimental studies in authentic classroom settings. Features beneficial for learning which are further enhanced by a robot compared to an agent are identified. These include embodiment of the robot; a social, empathic behaviour, better conversational abilities which together provide a better role model of an ideal learner for the student to identify with.