Abstract
Many students struggle to grasp the concept of limits, leading to persistent learning obstacles. This study employed a didactical design research (DDR) approach involving 56 mathematics education students at Universitas Khairun, divided into two groups. Data from tests, interviews, and teaching interventions revealed three key obstacles: epistemological (e.g., confusion between indeterminate and undefined forms like 0/0), ontogenic (e.g., difficulties with factoring and graphing), and didactical (e.g., misaligned instruction). A didactical design based on the Theory of Didactical Situations (TDS) was developed to address these challenges.