This study aims to examine mathematics teachers' interpretations of students' thinking within the scope of teaching experiments as a professional development activity. The method used in this study is a teaching experiment. The participants are 3 elementary school mathematics teachers. The teaching experiment consists of 5 teaching episodes and clinical interviews in each episode. The study was conducted in 15 weeks. The data collection tools consist of student solution sheets, written opinion forms, and video recordings of interviews and observation notes taken in clinical interviews after the application. Conceptual analysis of the data obtained from the teaching experiment was conducted as retrospective and prospective analysis. The results show that teachers developed the interpretation level of students' thinking by not only describing/commenting on students' solutions but also making appropriate comments on students' solutions in the process of teaching experiments. Considering that teachers can structure the content of their courses and classroom interaction based on students' different ways of thinking, it is believed that this study will provide foresight for future studies.