This study investigates 3rd graders' thinking process in net-game from what the pupils wrote in class records. This study reveals three findings; introduction of competing game after playing collaborative game to enhance pupils' ball control ability; devising rules that allow enough time for the ball control can smoothly elicit pupils' strategic thinking in offence; in such situation, their thoughts associated with "offence", "sequence (for offence)" in order. Implications of this study are discussed to explore a lesson planning for the relationship between individual and group, focusing on each pupil's thought and movement, and the interaction with other classmates for future study.