Purpose: This study was conducted to investigate and identify middle school science teachers’ level of conceptual understanding of the concept of matter, its properties, and changes of state, as well as to identify their potential misconceptions in this domain.
Methods: This study employed a two-tier diagnostic instrument consisting of 11 questions on the concept of matter, its properties, and changes of state. The questions were developed based on previous studies on students’ misconceptions. To further examine and validate the findings of the two-tier test, semi-structured telephone interviews were conducted with eight science teachers. The study population consisted of middle school science teachers in Mazandaran Province during the 2024-2025 academic year. A total of 109 teachers were randomly selected to participate in the study and completed the questionnaire.
Findings: The results showed that the highest levels of misconceptions among middle school science teachers were related to concepts of gas behavior, gas dissolution, and the particulate nature of matter, whereas the lowest level of misconceptions was associated with concepts related to chemical changes. Moreover, no significant relationship was found between teaching experience and the level of teachers’ misconceptions. The findings also indicated that some conceptual misconceptions persisted among teachers despite their teaching experience, and that some of these misconceptions were consistent with those reported among students in previous studies.
Results: These findings indicate that teaching experience alone is insufficient to eliminate middle school science teachers’ conceptual misconceptions, particularly those related to the concepts of matter and gas behavior. Therefore, revising teacher education programs and designing targeted in-service training programs with an emphasis on identifying and addressing conceptual misconceptions appear to be essential for improving the quality of science education.