A study on the classification of triangles by angles in elementary school mathematics. (Korean. English summary)

J. Korean Soc. Math. Educ., Ser. C, Educ. Prim. Sch. Math. 18, No. 1, 45-59 (2015).

Summary: This study focused on the classification of triangles by angles in elementary school mathematics. We examined the Korean national mathematics curriculum from the past to the present. We also examined foreign textbooks and Euclidâ€™s {\it Elements}. As a result, it is shown that the classification is not indispensable from the mathematical and the perceptual viewpoint. It is rather useful for students to know the names of triangles when studying upper level mathematics in middle and high schools. This study also suggested that the classification is introduced in elementary school mathematics in the context of reasoning and inquiring as shown in foreign textbooks, and example topics for the reasoning and inquiring.