Chemical represenattions: Use in textbooks and their role in learni̇ng

The purpose of this master thesis is twofold. First one is to analyze characteristics of chemical representations in electrochemistry in General Chemistry textbooks. Second aim is to investigate the effect on different representations on preservice science teachers' understanding of electrochemistry concepts. Content analysis of 17 General Chemistry textbooks was conducted in order to determine the characteristics of chemical representations in electrochemistry unit. During content analysis, an existing rubric, including criteria for analysis of representations, in textbooks was utilized to examine representations in electrochemistry unit. To investigate the effect on different representations on preservice science teachers' understanding of electrochemistry concepts, case study was used as a research design. Semi structured interviews were conducted with nine preservice science teachers to collect data during case study. Open ended questions were directed during semi structured interviews to reveal pre service teachers' understandings about representations, views about representations, understandings about electrochemistry concepts, views about teaching both chemistry and electrochemistry, and finally how different representations affect pre service teachers' understanding of related electrochemistry concept. Descriptive and content analyses were conducted for analyzing data obtained from semi-structured interviews were analyzed. Results of content analysis of General Chemistry textbooks indicated that number of representations in electrochemistry unit varies between 2 and 52 and total number of representations analyzed was 289. Average number of representations in each book was 17 independent from the publisher. Average number of representations in a page ranged between 0,11 and 1,22. Only two of the textbooks had at least one representation on a page. Most of the representations in electrochemistry unit were used during teaching of the topic (in text) while number of representations used in assessment part was less. With regard to type, hybrid and multiple representations were utilized most and macroscopic and mixed representations were the least frequent representations. More than half of the representations had explicit surface features and were completely related and linked to the text. Most of the representations' captions were found to be appropriate. When multiple representations were analyzed, it was observed that majority of multiple representations had sufficient links between their subordinates. Macroscopic and symbolic representations were the types that were mostly used together in multiple representations. Data obtained from semi-structured interview conducted in line with the second purpose of this study indicated that majority of the pre service science teachers has sufficient understanding about macroscopic representations while they had more difficulty in understanding submicroscopic and multiple representations. When the effect of different representations on pre service science teachers' understandings about electrochemistry concepts was analyzed, it was observed that there was an increase in the number of correct concepts when text related to the representation was presented to students. In terms of the text's effect on understanding about representations, there was no change in pre service science teachers' understandings of representations and were fewer pre service teachers of whom their understandings about symbolic and multiple representations increased. Pre service science teachers found macroscopic representation ineffective and both multiple and symbolic representations effective for teaching. With the existence of text related to the representation, number of pre service teachers finding multiple and symbolic representations adequate was increased. Number of the pre service science teachers found the text related to the representation as sufficient for macroscopic, multiple, symbolic representations was a bit higher than the number of the pre service science teachers found the text related to the representation as partially sufficient. More than half of the pre service teachers had partial understandings about the basic concepts about Galvanic cells while one fourth of the pre service science teachers had no understanding. The findings of this study also revealed that oxidation, reduction, electrode, anode, cathode, half-cell, cell potential and, and Galvanic cell were the concepts that most of the pre service teachers had partial or no understanding. Based on the findings revealed from this master thesis, recommendations for textbook writers, science teachers, science teacher educators, and implications for science education researchers were provided.