The purpose of this study was to conduct a lesson unit for fourth graders focusing on divergent and convergent thinking in flag football strategy planning, and to analyze changes in the students strategy planning before and after the lesson unit. The participants were 64 fourth-grade students. We conducted a paper-based strategies planning test before and after a lesson unit consisting of eight flag football physical education (PE) classes. During the first half of the lesson unit, we set goals for students to present their ideas and plan various strategies, and during the second half, we provided specialized instructions in selecting and modifying effective strategies. The strategies planning test was analyzed from the perspectives of divergent thinking i.e., number and concreteness of plans, and convergent thinking i.e., number and appropriateness of plans.The main results following the strategies planning test are below:(1) The number of strategies planned by the students increased.(2) Furthermore, the number of strategies on how to decoy players and the defensive players moves led to an increase in the percentage of concrete strategies.(3) The percentage of strategies on attacking places without defensive players increased.These results confirmed that the students were planning more concrete strategies through the lesson unit and thus, their divergent thinking had improved. In addition, the students came together to plan a strategy, assuming they would attack a place without defensive players and thus, their convergent thinking had improved. Therefore, it can be said that the lesson unit was an example of effective methods to promote divergent and convergent thinking of strategy planning by children.