This article analyzes an episode of classroom mathematics activity mediated by graphing technology from 3 different theoretical perspectives. An important line of research in the learning sciences focuses on graphs as "inscriptions", foregrounding learners' interactions with and around the material properties of graphical displays. Several recent studies in mathematics education have emphasized the utility of an "instrumental genesis" approach for conceptualizing mathematics learning and teaching with graphing calculators and other tools. A third perspective, influential in science and technology studies but less widely used in education research, calls for attention to "material agency", considering the ways both learners and tools might be conceptualized as actors in a classroom activity system. This article explores the potential of this alternate approach for extending insights into technology-supported mathematics teaching and learning. It is argued that a material agency account can complement and enrich theoretical frameworks for analyzing technology-mediated classroom activity. Collectively, drawing these perspectives together to examine a classroom episode in which a digital device played a pivotal role provides a framework for considering the complexities and the tradeoffs involved in cultivating proficient tool use and conceptual understanding in contemporary mathematics classrooms.