What makes an effective engineering diagram? A comparative study of novices and experts

Engineers have a predictable way of working. A text (T) or verbal description of a problem is translated into a diagram (D) which bootstraps the creation of a symbolic/mathematical (S) model for further analysis. Learning to solve problems in this particular way is a major goal for engineering education. The research presented in this paper focuses specifically on the text to diagram translation and the particularized representations utilized within a course on conservation principles. Previous research on student-generated diagrams revealed that, at the beginning of the course, students are not able to construct useful diagrams that follow the conservation laws. This result led to the general question of whether students can recognize useful, correct diagrams; more specifically: 1) Given a set of diagrams, are students able to distinguish between effective and ineffective diagrams? and 2) How do students’ judgments compare with those of an expert? To answer these questions, we conducted an exploratory study of students’ ranking of a set of diagrams for a complex, multi-unit problem. We compared them to those of an expert using Spearman’s Rank Correlation Coefficient in a cluster analysis. These findings are complimented by results from the post-exercise class discussion regarding criteria for a good diagram and have important implications for teaching and for future research.