Within whiteness, the organization of social life is in terms of a center and margins that are based on dominance, control, and a transcendent figure that is consistently and structurally ascribed value over and above other figures. In this paper, we synthesize literature from Critical Whiteness Studies and Critical Race Theory to articulate analytic markers for whiteness, and use the markers to identify and analyze whiteness as it shows up in an introductory physics classroom interaction. We name mechanisms that facilitate the reproduction of whiteness in this local context, including a particular representation of energy, physics values, whiteboards, gendered social norms, and the structure of schooling. In naming whiteness and offering a set of analytic markers, our aim is to provide instructors and researchers with a tool for identifying whiteness in their own contexts. Alongside our discussion, which imagines new possibilities for physics teaching and learning, we hope our work contributes to Critical Whiteness Studies' goal of dismantling whiteness.