Place of thought experiments in problems solving about lifting force and pressure

This study is a case study made up of two phases that respectively aimed at determining thought experiments developed by students and determining the structures of them.The first phase of the study was applied to 30, 9th grade and 28, 11th grade students in Anatolian High School. A scale which was prepared with expert opinions about the subject of Lifting Force and Pressure, and consisting of 4 open-ended questions was used and the answers given by students were evaluated by two different teachers. In addition, the average difficulty level of test questions was determined and through item analysis the questions asked in the test were found to be of intermediate level.In the second phase, semi-structured interviews were carried out with 4, 9th grade and 4, 11th grade students who were included in the first session voluntarily in the thought experiments where they would perform and that were consisted of the same questions. The data obtained were encoded in terms of the fact that they would be able to design a thought experiment. As a result of the analyses of the data, the emerging structures of thought experiments were compared, and differences and similarities between classes were discussed. A significant difference was found between two classes in favor of 11th class.Key words: Thought Experiments, Physics Education, Lifting Force, Liquid and Air Pressure