ABSTRACT
This chapter was motivated by a desire to investigate the ways in which children talked about and explained their mathematical solutions and thinking in the project classroom where mathematics instruction followed an inquiry tradition. In this tradition, instruction is designed to engage children in meaningful mathematical activity, including explaining and justifying their thinking to others (Cobb, Wood, Yackel, & McNeal, 1992). Other chapters in this book deal with languaging more generally (Bauersfeld, chap. 8, this volume) and with the development of argumentation (Krummheuer, chap. 7, this volume).
