The characteristics of diagrams in scientific explanations: Multimodal integration of written and visual modes of representation in junior high school textbooks.

There is a growing research examining the use of visual diagrams in scientific explanations. However, current research in this area is mostly based on case studies involving a few explanations from one or two topics in science. There are few systematic studies that examine more broadly how diagrams are used in relation to scientific explanations across a range of scientific texts. The aim of this study is to investigate the characteristics of diagrams in scientific explanations found in Grade 7–10 science textbooks covering many topics in biology, chemistry, earth and space sciences, and physics. The study is informed by the theories of systemic functional linguistics and social semiotics and applies a mixed methods approach to textbook analysis. A content analysis was first carried out to systematically identify the image functions (e.g., narrative, analytical, classificational) in all the diagrams (N = 749) and compare their distributions across different genres (e.g., explanation, information, experiment). This is followed by a multimodal discourse analysis to understand how the various image functions are combined with the linguistic features of the written text in the construction of scientific explanations. Quantitative results reveal explanation diagrams are characteristically different from diagrams used in other genres in terms of a higher usage of narrative function, temporal function, and annotated caption. Qualitative results further show how these image functions are typically used to support the reasoning of the explanation focusing on dynamic processes and time‐bounded sequences. This study has implications to our understanding of how diagrams are used to support the construction of scientific explanations. [ABSTRACT FROM AUTHOR]