Over the past two decades, science educators increasingly have become interested in the role of language in the learning of science and have drawn on the work of Bakhtin, among others, for understanding the dialogical nature of knowledge in a sociocultural framework. However, the nature of language and its relation to thinking have not substantially changed and, in many ways, are incommensurable with the cultural-historical, materialist dialectical underpinning of the original framing of the sociocultural and dialogical approaches in the theories of L. S. Vygotsky and M. M. Bakhtin and his circle (e.g., V. N. Voloꩮov). Most importantly, currently available analyses of science classroom talk do not appear to exhibit sufficient appreciation of the fact that words, statements, and language are living phenomena, that is, they inherently change in speaking. In this paper, I begin by working out the premise that language is a living phenomenon that changes in use. I then present two key insights on language-in-use that derive from the works of Vygotsky and the Bakhtin circle, which are used to develop a theoretical and methodological frame. These key insights and the theoretical aspects of this paper are exemplified with materials from a concept mapping session in a 12th-grade physics course. The proposed model has considerable implications for theorizing the relation between classroom talk and formal written genres of expression, and gives rise to many new research questions. 頲014 Wiley Periodicals, Inc. J Res Sci Teach 51: 1049-1083, 2014