This research aims to explore students' learning obstacles in solving fraction problems in elementary school. This qualitative research used a case study method. The research subjects involved 30 third-grade elementary school students from two different schools in Bandung City, Indonesia. The instruments utilized were test and non-test. The test technique was done by giving fractional material questions, while the non-test technique was in the form of interviews. The data collected were then analyzed employing the three stages of the Miles and Huberman model, including data reduction, data presentation, and drawing conclusions. The study findings revealed that students experienced epistemological obstacles, where students experienced limited knowledge, ranging from the basic concepts of fractions, fractional arithmetic operations, and fraction problem-solving. Based on these findings, teachers can construct learning designs with appropriate didactic situations as a follow-up to minimize the occurrence of similar learning obstacles in future fractional learning materials.

In teaching, students' representations could constitute an obstacle to the construction of scientific knowledge and are often considered stable cognitive structures whose organization is sought to be inferred through questionnaires and interviews. This study aims at identifying and analyzing high school students’ representations related to the concept of biodiversity. To meet this objective, a semi-structured interview and a questionnaire were used to collect data. 202 Moroccan students participated in this survey (46.5% from rural areas and 53.5% from urban areas of the "Direction Provinciale" of education of Guelmim city in Morocco). The results of the interview indicated that only 1.82% of the students gave a definition that consists of the three biodiversity dimensions, namely the species, the ecosystems, and the genetic diversity. The questionnaire results revealed a low to medium correlation between their representations and their acquired knowledge related to the concept of biodiversity dealt with in Moroccan school programs (from the discipline of "scientific activity" in the primary cycle and that of "life and earth sciences" in the secondary cycle). The results further indicated a low presence of supervised activities related to biodiversity within the school and therefore a low degree of influence on the students' representations. It was concluded that there was no effective transmission or adequate assimilation of the concept of biodiversity among the students surveyed.