Representations of chemical phenomena in secondary school chemistry textbooks

The difficulties encountered by students in learning chemistry range from human factors to the intrinsic nature of chemistry. To enhance students' understanding of chemistry, there is a wide consensus within the community of chemistry educators on the importance of and need to integrate different levels of representations in chemistry teaching and learning resources. As learning resources, textbooks are ubiquitous and usually readily available to both students and teachers. Therefore, this study investigated how chemical phenomena are represented or depicted in secondary school chemistry textbooks. We adopted a rubric developed by Gkitzia et al. (Gkitzia V., Salta K. and Tzougraki C., (2011), Development and application of suitable criteria for the evaluation of chemical representations in school textbooks, Chem. Educ. Res. Pract., 12, 5-14) to analyze the textbooks for types of representations; relatedness of chemical representations to text; and the appropriateness of captions. The results indicated the dominance of symbolic representations, followed by sub-microscopic, then hybrid and multiple representations. In all three textbooks, there was no evidence of mixed representation. While many of the chemical representations were completely related to the texts, some were unlinked. The germaneness of suitable captions in textbooks is in the explicit, brief and concise explanation that captions give to an entire representation. While our results indicated that more than half of the representations had suitable captions, there was evidence of representations that were problematic and had no captions. The implication of these results for students' cognitive load, and the need for textbook-users to explore alternative resources that depict phenomena in 2D or 3D representations are discussed.