Intrigued by the wide range of pupils' responses to a sourcebased essay question, Jonathan Sellin decided to investigate why pupils were using sources in such different ways. Probing his own philosophical assumptions about history, and how they have changed over time, prompted Sellin to explore pupils' assumptions about how historians use sources to make claims about the past. By asking pupils to create drawings about the methods used by historians to analyse sources, Sellin arrived at tentative conclusions about why his pupils were approaching the same essay question in different ways. This investigation led him to reconsider how and where he uses sources in the classroom, and the language that he uses to discuss sources and evidence. His reflections on pupils' drawings and essays have made him more determined to tackle pupils' misconceptions more directly, and to model how historians use sources in their scholarship more regularly.