This research is a reversal of the traditional concept of the student-teaching research experiment. Instead of studying the clear and stated goal of an apprenticeship, that of a pupil learning from the tutelage of a master, the focus here is on what a mentor-teacher learns from a student-teacher. During the act of teaching a novice, what can a mentor-teacher learn about her own practice, while demonstrating it to a pre-service teacher? Using the conceptual framework of the National Board for Professional Teaching Standards' Architecture of Accomplished Teaching, and using it within a framework centered around cognitive coaching and reciprocal mentoring, this action research study implemented an intervention that called for series of five cognitive coaching cycles between a mentor- and student-teacher designed to foster dialogue and reflection between them. The ultimate aim of this case study was to help determine what a mentor-teacher learned about her own practice as a result of mentoring a student-teacher. Qualitative data were collected over sixteen weeks in a charter high school. Five findings were identified created after the data were analyzed using a grounded theory approach, and four conclusions were drawn about the intervention's role in the mentor-teacher's reciprocal learning.