This study was motivated by the statement that mathematics is a difficult subject. Many students experience difficulties in learning mathematics. This study focuses on answering this rumor from the perspective of elementary school/MI teachers. What difficulties do teachers experience when teaching mathematics, resulting in students having difficulty understanding the material? The objectives of this study are 1) to analyze which mathematics material is considered most difficult by students, 2) why students have difficulty learning this mathematics material, 3) what difficulties students experience when learning mathematics, 4) what difficulties elementary school/MI teachers experience when teaching mathematics, and 5) what kind of mathematics learning should be carried out in the classroom. This study used a survey method, with the population being elementary school/MI teachers on the island of Java, Indonesia. Meanwhile, the sample data was obtained from elementary school/MI teachers spread across the Java region, such as West Java Province, DKI Jakarta, Banten, etc., with 133 respondents. The instrument used was a questionnaire filled out via Google Form and Mentimeter links. The results of the study reveal 1) several mathematics materials that are considered most difficult by students, 2) several factors causing students to experience difficulties in learning mathematics, 3) a mapping of the difficulties students experience when learning mathematics, 4) a grouping of the difficulties that elementary school/MI teachers experience in teaching mathematics, and 5) suggestions for mathematics learning that should be carried out in the classroom.