摘要：Abstract. This research is motivated by the epistemological difficulties of students in mathematical concepts. This research aims to make a didactic design in courses of Mathematics Basic Concepts. The method used in this research is Didactic Design Research (DDR). This research was conducted at the University majoring in Elementary School Teacher Education in the first semester in Riau, who attended in courses of Mathematics Basic Concepts as many as 43 students. Data collection techniques in this research were carried out by triangulation which is a combination of written tests, interviews and documentation studies, with data sources of students and lecturers. The results of the study were didactic designs consisting of three learning designs. Didactic design was developed through three stages. Firstly arranging an initial didactic design based on student difficulties, secondly a metaphorical notation analysis is carried out while learning takes place and thirdly a retrospective analysis is done by comparing the results of the initial obstacle learning test and the results of the final obstacle learning test. The retrospective analysis carried out by comparing the results of the initial obstacle learning test and the results of the final obstacle learning test. Result shows that there are fewer student learning difficulties and some are still happening, so that a revised didactic design is needed to improve the initial didactic design so that student learning difficulties can be overcome. The results of the didactic design implementation of students' mathematical reasoning concepts are in accordance with the predictions of the responses made. Keywords: Didactic Design, Mathematical Reasoning, Learning Obstacle, Retrospective Analysis.
