This presentation reports on a study that traces the mediating work of two teachers as they guide students preparing to write the degree project essay through exploratory exercises designed to help them pose a genuine question in response to a disciplinary-specific problem. The study examines written exchanges in discussion forums in which teachers challenge students to focus their thinking at the discovery stage of the writing process. According to rhetorical pedagogical theory, exploratory exercises empower students by giving them insider knowledge of discourse strategies. However, this study finds that it is not enough to direct students to exploratory exercises for self-study. Students new to research writing benefit from the mediating guidance of teachers. The analysis shows how students develop their arguments in response to teacher interventions. Results show that mediating teachers can enhance the heuristic value of exploratory exercises by scaffolding students while also promoting their autonomy.