Experimental evidence has shown the effect of peer-group argumentation on scientific concept development. However, questions regarding how and why it happens remain. The aim of this study is to contribute, with experimental evidence gathered in naturalistic settings (classrooms), to the understanding of the relationship between peer-group…

This article describes how teachers can use students' conversations to assess their mathematical understanding. The authors draw on their own classroom experiences to show what they learned about planning for future lessons based on discussions in their own classrooms.