APOS, which Dubinsky developed, is a constructivist learning theory based on Piaget's epistemology. This theory has been adopted all over the world to teach mathematics. Students benefit from a better understanding of mathematical concepts thanks to the application of the APOS theory in mathematics education, which contributes to the overall formation and development of the student's mathematical abilities. This research was carried out to lay the groundwork for subsequent research that will apply APOS theory to instructing high school teachers on derivatives. The research was conducted with forty high school teacher participants to survey their understanding and perspectives on mathematical competencies in general, problem-solving capacity in particular, and APOS theory in teaching the topic of derivatives. According to the research findings, most teachers understood the significance of their role in assisting students in acquiring new skills and appreciate the weight of this responsibility (especially the ability to solve mathematical problems). On the other hand, the majority of the teachers who took part in this survey had only a very basic comprehension of the APOS theory.