Previous studies were conducted with 14- to 15-year-old students on the nature of the processes they used to solve tasks given the incorrect/buggy/mal-rules. The computer-based Leeds Modelling System (LMS) was implemented and a database of examples, correct and incorrect, or mal-rules had been established which was sufficient to diagnose the…

A group of 24 14-year-old students were presented with sets of algebra tasks using the Leeds Modelling System (LMS), a computer-based modeling system. Four months later, these same students were given a paper-and-pencil test which covered comparable tasks set by LMS. In addition, certain students were given detailed diagnostic interviews. A…

This paper reports the results obtained with a group of 24 14-year-old students when presented with a set of algebra tasks by the Leeds Modelling System (LMS). These same students were given a comparable paper-and-pencil test and detailed interviews some 4 months later. The latter studies uncovered several kinds of student misunderstanding that…