This study examined the effects of comparison and game-challenge strategies on sixth graders' learning achievement of algebra variable, learning attitude towards algebra variable learning, and meta-cognitive awareness of algebra variable learning. A 2 × 2 factorial design was used, and 86 students were invited to participate in the experimental instruction and assigned to four groups: comparison with game-challenge, comparison, game-challenge, and control. The results showed that (1) a significant interaction effect was found on students' learning achievement of algebra variable: the comparison with game-challenge group performed significantly better than the comparison group and the game-challenge group respectively; (2) a significant interaction effect was found on students' learning attitude towards algebra variable: the comparison with game-challenge group responded significantly more positively than the comparison group and the game-challenge group respectively; and (3) a significant interaction effect was found on students' meta-cognitive awareness of algebra variable learning: the comparison with game-challenge group reported significantly higher scores than the comparison group and the game-challenge group respectively.