The authors describe and discuss an activity in which primary school students were instructed how to use graph theory to solve a spatial puzzle. This activity was aligned with the design principles of vicarious failure. They discuss how this impacted the type of dialogue observed in the classroom and found that students were more likely to focus on processes and strategies, rather than 'correct' answers. They believe this to be an outcome of the lesson design. They conclude with an exploration of how this positions incorrect answers as valid forms of mathematical knowledge in the classroom.