Oral argumentation in the classroom is an area of study that requires analytical tools to address its complexity. In this study a pragma-dialectical approach is used, in which dialectical and rhetorical analysis is used to examine the interaction of a group of eleventh grade students in an educational institution in the city of Vina del Mar (Chile), as they express their points of view and arguments about a controversial issue in a 45 minute Spanish class. In terms of the dialectical dimension, results show that, although the students met with the confrontation and argumentation stages of critical discussions, they did not include the opening and closure stages. In terms of the rhetoric dimension, they use strategic maneuvers when they include new topics appealing to diverse audiences, as well as some presentational devices such as rhetorical figures. © 2010 Universidad Central de Venezuela.