Diagrammatic Literacy in Secondary Science Education

Students in secondary science education seem to have difficulties with understanding diagrams. The present study focused on explanatory factors that predict students' difficulties with process diagrams, i.e., diagrams that describe a process consisting of components that are related by arrows. From 18 compulsory national Biology exams of secondary school pre-university students, all process diagram tasks (n = 64) were included in corpus. Features of the task, student, and diagram were related to the difficulty of that particular task, indicated by the cohort mean exam score. A hierarchical regression analysis showed main effects for (1) the cognitive task demand, (2) the familiarity of the components, and (3) the number of components in a diagram. All these main effects were in the expected direction. We also observed interactions. Within the category of tasks with a high cognitive demand, tasks about a diagram of which students have low prior content knowledge were more difficult than tasks about a diagram of which students have high prior content knowledge. Tasks with a high cognitive demand about a diagram with familiar arrows were, surprisingly, more difficult than tasks with a high cognitive demand about a diagram with unfamiliar arrows. This latter finding might be attributed to compensation for task difficulty by the large number of components in the diagrams involved. The final model explained 46 % of the variance in exam scores. These results suggest that students have difficulties (1) with tasks that require a deeper understanding when the content is new, (2) with diagrams that use unfamiliar component conventions, and (3) with diagrams that have a small number of components and are therefore probably more abstract.