This volume explores the nature of discourse in secondary and upper elementary mathematics and science classrooms. Chapters examine conditions that support or hinder teachers and students, in particular language learners, in employing language as a tool for learning. The volume provides rich oral and written language examples from a range of classroom contexts to illustrate how linguistic practices affect students' appropriation and display of disciplinary specific knowledge. Chapters further explore linguistic practices through with the support of discourse analytic models that foreground the authentic classroom data with the aim of understanding the dynamics of the classroom. The authors investigate the intersection between discourse and learning from a range of perspectives, including an examination of key concepts such as intertextuality, interaction, mediation, scaffolding, appropriation, and adaptations. This volume offers concrete suggestions on how teachers might benefit from a discourse approach to teaching in the areas of mathematics and science.