PPIG 2000 - 12th Annual Workshop
Experiences with Novices: The Importance of Graphical Representations in Supporting Mental Models
Carlisle E. George
Abstract: Recursion is an important problem solving technique used in programming. It is also a highly unfamiliar mental activity and many computing novices have difficult understanding recursion and applying recursive techniques in problem solving. Research studies have concluded that novices and experts differ in their mental models of recursion. Novices seem to possess various inadequate models of recursion especially the iterative or loop model. This paper examines whether novices who are aided in acquiring an expert’s mental model of recursion (the copies model) can effectively use this model in evaluating recursive algorithms. Results of a study indicated that a large percentage of novices who had previously demonstrated an understanding of the copies model (using explicit diagrammatic traces) failed do so when not using diagrammatic traces. In fact, they appeared to demonstrate evidence for the incorrect iterative or loop model when trying to mentally evaluate recursive programs. The results provide evidence that mental models are unstable and that graphical representations are a very necessary aid to retrieval of novices’ mental models. This suggests that the teaching of recursion may be best facilitated by teaching students how to simulate the execution of a recursive algorithm using diagrammatic traces.