Scaffolding with Object Diagrams in first Year Programming Classes: Some Unexpected Results

This paper reports on an experiment in which first year programming students were given explicit encouragement to use Object (Instance) diagrams when tracing code in multiple-choice questions. We conjectured that by providing scaffolding in this technique, students would be helped to understand the code better and that they would then continue to draw their own diagrams in similar situations. This turned out not to be the case. Although generally students who draw diagrams do better in questions that test their understanding of code behaviour and object referencing, our intervention does not appear to have helped students and the students who were exposed to the intervention were not more likely to go on to use the technique themselves.