How consistent were students in their use of relational or computational approaches
across the three groups of problems? Students were classified into three groups: those
students who used relational strategies across all three groups of problems (SR–Stable
Relational); those students who used only arithmetical or computational approaches across
all three groups of problems (SA–Stable Arithmetical); and those students whose thinking
was not consistent across the three groups (NS–Not Stable). The following rule was used.