Analysis of High School Students’ Reasoning and Understanding of Circle Properties

This study aims to analyze the ability of high school students to understand concepts and mathematical reasoning on the properties of circles. The study used a qualitative descriptive approach with a one-shot case study design, involving 20 students in class X of SMA Negeri 5 Cirebon who were selected through purposive sampling. Instruments in the form of post-tests are used to measure two cognitive aspects, namely concept understanding and mathematical reasoning. The results showed that the ability to understand concepts was higher than reasoning. As many as 80% of students were able to solve the circle area problem, and 90% were able to apply the juring area formula correctly, with an average comprehension score of 85. However, mathematical reasoning still varies, with an average score of 77.5; Only 75% of students can give rational reasons related to the shape of circles, and 80% are able to relate the concept of angles to daily life, and there are even students who get a score of 0. These findings show that conceptual mastery is not fully accompanied by reasoning skills, so it is necessary to apply problem-based learning strategies and the use of contextual interactive media to strengthen concept understanding while improving critical thinking skills and mathematical reasoning in a more meaningful way