Christine Counsell describes a lively activity, ideal for Year 9, in which pupils compare and interrelate a collection of sources. The activity leads pupils into thinking about the sources as a collection, and about the enquiry as an evidential problem. Or at least it can do. The article discusses the planning dimension that makes or breaks such an activity. Without a strong question focus, a clear knowledge context and deliberate use of prior learning, the activity is at best a missed opportunity and, at worst, leads to superficial judgement rather than historically rigorous and informed reflection. A practical idea alone, whilst appealing on the surface, is of very limited use without some underlying theory about its role in historical learning. The happy-sad continuum activity is used here as a imaginative tool for getting teachers to ‘think backwards' about what planning for progression in evidential understanding might mean. Christine suggests that, within reason, it can mean whatever history teachers want it to mean. It is up to history teachers to make it happen.