1. YOSHIHITO KINOSHITA (yk_an_enmachbi@yahoo.co.jp) is a graduate student in the Graduate School of Mathematics and Science Education, Tokyo University of Science (RIKADAI), Kagurazaka, Shinjuku, Tokyo, Japan.
2. TAKAHIRO YAMANOI (yamanoit@fc.hakuoh.ac.jp) is a Lecturer in the Faculty of Education, Hakuoh University, Oyama, Tochigi, Japan.
3. MASAHARU TAKEMURA (takemura@rs.kagu.tus.ac.jp) is an Associate Professor in the Graduate School of Mathematics and Science Education, Tokyo University of Science (RIKADAI), Kagurazaka, Shinjuku, Tokyo, Japan.