ABSTRACT
This chapter describes how 11- to 14-year-old students in England assess the correctness and equivalence of models and rules for figural linear patterns, following engagement with a carefully designed activity sequence. After the students express their own generalisations of the models presented to them in the environment's symbolic language, they engage in a collaborative activity aiming at justifying the correctness of their independent rules and discussing their equivalence. This chapter presents the results from this collaborative activity with data collected from 48 students from three different schools. It demonstrates how the combination of a system that integrates construction with expression and a carefully engineered collaborative task can influence positively students’ justifications for the correctness and equivalence of symbolic expressions, encouraging a structural sense in Algebra.
