This paper consists of a detailed analysis of how the participants in a debate build their emotional position during the interaction and how such a position is strongly related to the conclusion they defend. In this case study, teenage Mexican students, arguing about access to drinking water, display extensive discursive work on the emotional tonality given to the issue. Plantin's (2011) methodological tools are adopted to follow two alternative emotional framings produced by disagreeing students, starting from a common, highly negative, thymic tonality. Through the analysis of four parameters (distance to the problem ; causality/agentivity; possibility of control and conformity to the norms) we describe how the emotional dimension of schematization (Grize 1997) is argumentatively relevant. In authentic discourse, it is impossible to separate emotion from reason. The conclusion section discusses the implications for the design of argumentation-based pedagogical activities.