This paper focuses on working deliberately with secondary mathematics teachers on exemplification. The context is the Wits Maths Connect Secondary (WMCS) longitudinal research and professional development project in South Africa, where exemplification, specifically example sets informed by principles of variation, is a key focus in our work with teachers. We describe why we have come to focus on exemplification. We illustrate the what and how of this work through a selection of tasks where teachers are offered opportunity to learn about variance amidst invariance in example sets and what they afford.