Textbooks as source for conceptional confusion in teaching and learning ‘acids and bases’ in lower secondary school

Chemistry teaching and learning bears some subject-specific challenges. For example, explanations and considerations of chemical phenomena drawing on the macroscopic, the sub-microscopic and the representational level. In this paper, we focus on the topic ‘acids and bases’ where the confusion of these levels leads to numerous misconceptions among learners. One possible source of these problems are textbooks, which can have an important impact on the quality of teaching and learning. To identify scientific and didactical appropriate textbooks for lower secondary classes, we draw on the work of Roseman, J. E., Stern, L. & Koppal, M. (2010), who developed an instrument to analyse textbooks using a conceptual coherence map. To develop our topic-specific instrument, big ideas of the topic were formulated, arranged in a conceptual coherence map, and set in relation with each other. Then we development a coding manual that describes precisely how to apply the different categories while analysing textbooks. The process described is part of a design-based research project with the aim to contribute to better chemistry teaching and learning. We give insight into the process of developing this instrument for analysing chemistry textbooks. Furthermore, it presents some examples for problematic representations from textbooks in the field of ‘acids and bases’.