The study aims to identify the effectiveness of the Open Competition based on cooperative learning in the academic achievement of twelfth grade students in pure mathematics and the unit of integration. To achieve the objectives of the study, the researcher used the semi-experimental method. The study community consisted of all male students in the twelfth grade in Al Sharqiya Governorate (2032 students). The study sample was chosen in an intentional way, consisting of (60) students who were divided into two groups, an experimental group of (30) students, the open competition was applied while teaching thel, and a control group of (30) students who studied through the normal way. The study tools consist of the descriptive guide for the application of the Open Competition ( the teacher's guide ), and an achievement test in the integration unit. The study showed that there were no statistically significant differences between the two groups in the level of inference. Based on these results, the study reached a set of recommendation, most notably: activating the strategies of competition in general and the Open Competition in particular in the educational process because of their clear positive impact, and the inclusion of models of competition strategies that have proven effective educationally and behaviorally in the various curricula for mathematics. The study also recommended training mathematics teachers on how to deal with inference questions in terms of formulation, method of teaching, appropriate strategies and possible solutions, and sharpening their knowledge and skills.