Abstract
In the new course of study for mathematics in high schools that has started in 2012,
Euler’s formula was added as a new subject in mathematics A. In this reason, we developed
some teaching materials about Euler’s formula. In order to calculate the Euler number in the
sketch of a non-convex polyhedron, it is important for students to count the number ofvertices,
edges and faces correctly. However, when we had college students count the number of vertices,
edges and faces in the sketch, the percentage of correct answers was low.Therefore, as a
result of analyzing wrong answers and contents of answers, it turned out that there were
similarities in answer methods, and similarities in wrong figure recognition about vertices,
-edges and faces.
