This paper draws on data from a three-year longitudblal study of secondary school classrooms to examine pedagogical issues b~ using tectmology resources in mathematics teachhlg--hl particular, graphics calculators and overhead projection panels that allow screen output to be viewed by the whole class. We theorise four roles for technology in relation to such teachh~g and learning interactions--master, servant, partner, and extension of self--and illustrate this taxonomy with observational data from five senior secondary mathematics classrooms. Our research shows how technology can facilitate collaborative inquiry during both small group interactions and whole class discussions when students use their calculators and the overhead projection panel to share their mathematical understanding.