Recently, many mathematics teachers realized the importance of generating or reformulating a problem as well as solving a problem in U.S. and Australia (NCTM, 2000; Skinner, 1991). Moreover, Australia Education Association emphasized that encouraging students to pose their problems is a vital factor in education (HSU, 2006). In Japan, open-ended problems were improved for upgrading mathematics education by using problem posing at all levels to university (Hashimoto, 1997).