The use of graphical representations structures students' reasoning about a physical scenario or problem. Different graphical representations for energy in physical situations highlight different aspects of energy and therefore may represent and foster different conceptualizations of energy. One particular representation of energy dynamics in a physical system, the Energy-Interaction Diagram, embodies a Stores and Transfer model of energy. In this paper, I show how the Energy-Interaction Diagram can evoke productive resources for disciplinary engagement with energy. In the presented example, students in an introductory college physics course activated the resources indicator reasoning, systems thinking, and substance metaphor while employing the Energy-Interaction Diagram to make sense of a puzzling scenario: Two billiard balls on parallel incline tracks with different widths—why does one ball roll down the ramp faster than the other?