While game-based learning is regarded as an effective way to promote learners' motivation and engagement, nonetheless, simply introduce a game to learning doesn't inherently translate to effective learning. This study designed a game-based learning activity that incorporated a mini digital game with group discussions and teacher's guidance to teach the concept of the law of the lever. An action research was conducted to evaluate the learning activity. Results indicate that students generally enjoyed participating the game-based learning activity. In addition, students generally perceived the learning activity as useful in support their learning and easy to participate. Students' learning achievement was also significantly improved after the learning activity. The details of the learning activity design, the results of action research, as well as implications of the findings are to be delineated in this study.