This study aims to provide an effective unit for developing a pupil’s performance in ball games. Generally, pupils have to learn tactical knowledge and decision-making skills for both offense and defense to enhance their performance in ball games, as outlined in “Teaching Games for Understanding”. Furthermore, it is believed that modification of the full games is important for beginners to learn tactical knowledge and decision making in games. As a result, a flag football unit was developed involving both representation and exaggeration to assist learning in Physical Education. This unit incorporates tactical knowledge and decision making involved in both offensive and defensive aspects of the game.