In each issue of Heart , we publish an image challenge which consists of a brief clinical vignette, an image and an accompanying multiple choice question (MCQ), followed by a short discussion. The goal of the image challenge is to make an educational point, so authors must reflect on what they wish to teach. The clarity of the educational point is often what distinguishes a strong image challenge which is accepted for publication from those that are not. Even though the importance of a clearly defined teaching and testing point is self-evident, it is natural that the the inspiration to write an image challenge occurs when an author encounters a remarkable image in clinical practice and wishes to share it. High-quality and engaging images are critical, but the best image challenge submissions are not show-and-tell, in which the image is primary and the MCQ and teaching point are perfunctory. Rather, the image should be used to augment a well-crafted MCQ. MCQs, often maligned, can be effective educational tools; they require active learning, or what cognitive psychologists call ‘retrieval practice’, in which the reader deliberately recalls information which has been previously learnt.1 Retrieval practice improves long-term retention of information and allows clinicians to later recall that information in ‘real life’ and apply that information to a variety of …