This study explores the experiences of Grade 12 mathematics teachers in identifying and correcting misconceptions and errors in learners’ understanding of the concept of similarity in Euclidean geometry. The concept of similarity is a fundamental part of the mathematics curriculum, and misconceptions in this area can significantly hinder students’ ability to grasp advanced geometrical concepts. However, despite existing literature providing guidance on dealing with learner misconceptions in learning geometry there is still a notable research gap in understanding the specific experiences of teachers in identifying and correcting misconceptions about similarity. This is more so for South African schools in Grade 12. Existing studies have primarily focused on students’ misconceptions or generalized pedagogical strategies, with little emphasis on the practical application of teachers' pedagogical content knowledge (PCK) when addressing these misconceptions in the classroom.

This research report aims to provide insight into the challenges teachers encounter in identifying learners’ errors and misconceptions in geometry. This will be accompanied by the strategies they use in trying to help students achieve a correct understanding of the concepts. Following qualitative data collection methods, interviews were used in examining teachers' PCK in relation to Similarity in geometry. The findings reveal that while some teachers demonstrate a solid understanding of similarity, there is variability in their approaches to identifying and correcting misconceptions and errors, with some relying more on direct instruction while others employ more interactive or diagnostic techniques. Common challenges faced by teachers include the complexity of students’ misconceptions. As a result of the findings, recommendations for professional development programs that focus on enhancing teachers’ diagnostic skills and equipping them with more effective strategies to address misconceptions in geometry. This research contributes to the broader understanding of how teacher experiences shape their approach to teaching complex mathematical concepts and improving student learning outcomes, addressing a critical gap in the existing literature on teacher practices in correcting misconceptions in high school geometry.

Keywords: Misconceptions, errors, similarity, Euclidean geometry, pedagogical content knowledge, teaching strategies, teacher experiences, professional development, diagnostic skills, high school mathematics.