Layers of competence: analyzing 8th graders’ perceptions of visual and verbal assessment questions on chemical processes <i>vis-à-vis</i> their performance

The design of assessments shapes what we learn about students’ conceptual understanding. In the context of chemistry education, visual representations are important components of learning and assessment. To examine the role of representations in assessing students’ reasoning about chemical and physical changes, we developed two multiple choice questionnaires: one that represents the choice options in verbal form and one that represents isomorphic options – in pictures. The questionnaires included a second-tier rating scale of the questions’ general comprehensibility and the clarity of the pictures. The questionnaires were distributed among 374 eighth graders in two phases. In the first phase we found that on average, students performed slightly better on the verbal version, and some verbal items were significantly easier than their visual counterparts, but one item showed the opposite trend. Interviews revealed that visual representations exposed a wider range of ideas among respondents, and in some cases, created confusion. The second phase focused on the visual version and revealed significant positive correlations between clarity judgements and performance in questions with visuals such as graphs that represent the change in mass and molecular structures that represent the chemical formula, and no correlations on others. The analysis of the interviews, together with the clarity ratings, indicates that in these questions, visuals can be conceived as an additional layer of challenge, while other questions entail conceptual misunderstandings that are either exposed or concealed by cues in the external, visual layer.