In this paper we address the ways in which surgeons, in collaboration with other members of the surgical team, create occasions for demonstration and instruction within the highly complex and demanding tasks of a surgical operation. Drawing on video recordings of surgical operations, augmented by field studies, we examine how particular phenomena and procedures are made accessible and intelligible to trainees and the ways in which brief episodes of insight and instruction enable complex procedures to be followed and understood. We consider the ways in which demonstration and instruction are achieved, whilst preserving the integrity of medical practice, and explore how trainees are provided with the opportunity to witness, and learn from, the contingent deployment of formal procedures in particular cases. We conclude by considering our observations in the light of recent discussions of practice and situated learning in healthcare training.