This paper discusses Betty’s Brain, a teachable agent in the domain of ecosystems that combines learning by teaching with self-regulation mentoring to promote deep learning and understanding. Two studies demonstrate the effectiveness of this system. The first study focused on components that define student-teacher interactions in the learning by teaching task. The second study examined the value of adding metacognitive strategies that governed Betty’s behavior and selfregulation hints provided by a mentor agent. The study compared three versions: an intelligent tutoring version, a learning by teaching version, and a learning by teaching plus selfregulation strategies. Results indicate that the addition of the self-regulation mentor better prepared students to learn new concepts later, even when they no longer had access to the self-regulation environment
