The purpose of this paper is to compare and analyze the two different teaching methods of elementary mathematics in the traditional method and in the constructive view. To do so, the actual class in the constructive view has been made for about four months using a class of 45 students in the second grade of an elementary school. After the class was finished, we collected diverse data from the class, such as the responses from the children(self-evaluation, mathematics diary, observation by the investigator, daily report), class evaluation report by other teacher and so on. The results of this research are as follows: First, the traditional class reaches at the goal of learning in a unit time because the class is guided by the teacher but the class in the constructive view is a little flexible because it is contextual. Second, in the constructive process of mathematical knowledge we knew that small group activities or discussion without intervention of teacher was often ended in exhaustive argument without arriving at valid social consensus. Third, the attitude in mathematics was changed from the passive one to the self-regulated ones. Fourth, the class in the constructive view could extend not only the ability of mathematical communication but also the ability of self-directed learning of children. Fifth, it was a considerable change the role of teacher, that is, guide of instruction instead of unique specialist in the classroom. Sixth, finally, the evaluation was made after finishing a unit class in the traditional instruction but it was integrated in a class in a constructive view.