Certain concepts in mathematics may function as cognitive obstacles for the students of secondary, or even those of tertiary education. These concepts are difficult for them to understand. In this paper, we highlight the concepts of epistemological, cognitive, and didactical obstacles, and we explain the significance of each one them, and how they arise, and how they can be bypassed. Moreover, we suggest that the adoption and use of these fundamental concepts of mathematics in the teaching-learning process early in the primary education, can definitely function as an advance organizer or as a means of scaffolding. According to the theory of Ausubel, this process will facilitate students’ attempts to overcome the problem of not understanding these concepts. Finally, we refer to examples of such concepts, and useful conclusions are made.