In the study of arithmetic and mathematics, it is very important to observe familiar phenomena and to model them from the mathematical point of view. For this purpose, many teaching materials have been provided so far, and its importance has been shown. This sort of activities of students always accompanies trial and error. By repeating trial and error, students accumulate a lot of experiences which make further improvement and progress. Their teaching materials have been practiced in the elective subjects and integrated studies. But, the new Guidelines for Course of study say that the total number of classes of elective subjects and integrated studies should reduce and that of required subjects should increase. Therefore, in near future, we need to practice the teaching materials mentioned above in the required subjects. In this paper, we make up “blowgun darts” as a mathematics teaching material in the required subject, so that students can experience the usefulness of mathematics. We report the practice of program “Mathematics in Blowgun Darts”.