ABSTRACT
This study aimed to analyze the effect of two-dimensional geometry learning on the geometric thinking of undergraduate students during the COVID-19 pandemic. This qualitative research involved students in the sixth semester. Data were collected using documentation, test descriptions, and interviews. The results showed there are some reasons why the students faced difficulty in mastering a higher level of geometric thinking: The lack of understanding of the concepts in geometry, the lack of knowledge of the definitions of terms and statements, and how to use them to prove. This study concludes that the variation in the geometric thinking level of undergraduate students shows that there are various students' abilities in two-dimensional geometry, starting from mastering concepts, definitions, and theorems to their use in proof. The suggestion is that several strategies are needed to serve these variations, starting from learning assistance and using diverse learning media. Stakeholders, teachers, and prospective teachers can use the results of this study to improve their understanding of geometry and how to teach it in schools. © 2023, North American Business Press. All rights reserved.