In this paper we consider the way moral meanings are created, expressed, and negotiated in the actions and words of participants as they engage in a collaborative science activity. The paper offers an analysis of two extracts from a video recording of a third-grade classroom in which two students, Jessica and Alan, work with each other and with a visiting teacher in conducting an experiment that concerns the refraction of light. Following Jackson et al. (1993) we explore the central role of expressive morality, the subtle and elusive ways in which moral messages inhere in all aspects of classroom interaction, including the teacher's tone of voice, gestures, proxemics, and choice of language. Our examination of the activity addresses the question: what kinds of moral relations are being created in this classroom? In addressing this question, we pay particular attention to the moral nature of the teacher's relation (Noddings, 1984(Noddings, , 1992 and interactions with each of the children; and the moral consequences of competence (or lack of it) in the forms of discourse that are privileged in the activity.