Getting to the Why : Teacher Practices that Support Mathematically Sound Student Justifications

Though the mathematical and education communities both value justification and argumentation in the middle grades classroom, teachers have historically found these practices difficult to support. This article discusses teaching practices that are associated with high levels of mathematically acceptable argumentation by students. Data were collected on seven committed teachers who explored justification and then implemented the same justification task over two years. Thus, the data reflected fourteen different implementations of the same task, allowing us to compare lessons directly. The findings describe how teachers’ Focusing Students’ Mathematics and Providing Scaffolding Questions are consistently associated with high levels of justification, while Leveraging a Critical Classroom Community and Providing Task Specific Tools are only sometimes associated an increased level of justification in a classroom. There are implications for teachers wishing to implement their own justification tasks, and researchers wishing to further study justification at the middle school level