Investigation of multiple representations of matter and heat unit in comparison with the cognitive structures of middle school students

Purpose: The purpose of the study is to examine multiple representations of the matter and heat unit by comparing them with the cognitive structures of secondary school students. Materials and Methods: The first phase of the study is the document analysis method, the second phase is an instrumental case study, and the third phase is content analysis. The first aim of the study is to examine the concepts and processes related to matter and heat unit in textbooks and textbooks in terms of multiple representations. The textbooks and course notebooks used in the Science course were analyzed descriptively in accordance with the criteria and code list created by Gkitzia, Salta and Tzougraki (2011). For the first sub-problem of the research, three sixth grade textbooks from the Science textbooks used in the 2022-2023 academic year in secondary schools, determined by the Ministry of Education (Tebliğler Magazine, 2019), were selected according to the non-random purpose sampling method. Course notebooks were selected from students who kept regular notebooks from five branches. The second aim of this study is to examine students' cognitive structures regarding the matter and heat unit. An instrumental case study was used for the second sub-problem of the research. The open-ended questions applied to 6th grade students were analyzed using the word association test. The sample of the study consisted of 30 randomly selected 6th grade students at the secondary school affiliated with the Ministry of National Education in Çine district of Aydın province. The third aim of the study is to examine students' cognitive structures by comparing them with multiple representations. The content analysis method was used for the third sub-problem in the study. Findings: In the study, it was determined that the textbooks included multiple representations mostly in the macroscopic dimension and least in the symbolic dimension. Macroscopic and microscopic visuals were included in equal numbers in the textbooks. When the cognitive structures of the students were examined, it was determined that the concepts of solid, liquid and gas were included more in the frequency tables. Later, these concepts were followed by concepts such as melting, freezing, evaporation, mass and volume. In the sentences made, sentences were made about the states of matter and its change of state. In the visuals drawn, drawings were made about the states of matter, the state change of matter and the granular structure of matter. When the cognitive structure was examined with multiple representations, it was determined that students made macroscopic drawings and gave less space to symbolic and microscopic drawings. Animations, visuals, three-dimensional models and mock-ups related to multiple representations can be used in the Science course. Result: It was determined that students mostly structured information in the macroscopic representation dimension. It was concluded that the 6th grade students participating in the research included the information in the 'Matter and Heat' unit in their superficial cognitive structures. In terms of demonstrability, the macroscopic dimension, which is revealed through concrete methods such as experiments and observations, is more present in students' cognitive structures than the microscopic and symbolic dimensions. In addition, it was concluded that they had difficulty in making connections between macroscopic, microscopic and symbolic dimensions and could not switch between the three types of representations. Key words: Multiple Notations, Textbook, Matter and Heat, Word Association Test, Cognitive Structure.