In this paper, we identified several problems in Korea elementary mathematics textbooks based on mathematical and didactical analysis upon angle and angle measurement concept. Moreover, we suggested new directions in teaching those concepts. Firstly, Euclid’s informal definition unfolded to inappropriate in elementary mathematics system, so, we need to replace that definition into more intuitive and operative definition. Secondly, when we standardize angle degree unit, we need to making a reference to whole circle rather than right angle. So, the works of proving
a theorem that sum of a triangle’s internal angle is 180°and of rotating figures by various angles are performed more harmoniously.