In this research project, we developed computer software to allow a pupil to operate sentences of arithmetic word problems, numerical expressions, and whole-part relations. We then and designed a curriculum to promote student comprehension of the structure of arithmetic word problems by using this software. We conducted practical teaching following the curriculum and based on the software for one second-grade class and two third-grade classes, with 10 class sessions in total. Through the practical use, we have confirmed that the software and curriculum were useful to promote student comprehension of the structure of arithmetic word problems by measuring their problem-posing performance.