A serious game, which is designed for learning purposes rather than recreational purposes, has been applied for digital game-based Learning. This study investigated the effects of graphic organizers in a serious game, "The Transistor", on learning outcomes and attitudinal perceptions. A total of 99 participants were randomly assigned to three groups: non-organizer group, advance organizer group, and post organizer group. The results revealed that participants using a post organizer, which was presented after the game for review, outperformed those using a non-organizer and an advance organizer on both learning outcomes (recall test scores and recycling intention) and attitudinal perceptions (perceived enjoyment, perceived usefulness, and satisfaction). These findings implied that a post-graphic organizer could enhance the instructional value of a serious game. More detailed implications, limitations, and suggestions for future research are discussed.