The preliminary study showed that the main problem, however, faced by kindergarten students are lack of mathematics skill, such arithmetic ability in kindergarten Galis. Therefore, the present study aims to investigate the effectiveness of a modified bottle cap as an educational game tool towards enhancement of arithmetic ability. Samples were prepared for the quasi-experiment research design involving 60 children, aged 4-5 years. A detailed comparison is made between the experimental condition, consisted of 30 students, received the educational game tool activities and the control condition which consisted of 30 students, received the instructional activities as usual. Before and after two weeks of the intervention with the game tool of a modified bottle cap, measures of arithmetic ability were administered to either experiment or control class. 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