The meta-analysis focuses on examining the effects of context-based learning on students' academic achievement and learning retention. A comprehensive search of the available research literature identified a total of 42 studies addressing academic achievement and 10 studies investigating learning retention. The findings of the analysis indicated that context-based learning had a statistically significant positive impact on both academic achievement (g=0.970) and learning retention (g=0.791) when compared to teacher-led instruction. These results were obtained using the random-effects model. To ensure the robustness of the findings, an assessment for publication bias was conducted. The analysis suggested that the observed effects were not influenced by publication bias. However, it is important to note that there was a notable variability in effect sizes across the included studies. To explore potential factors contributing to this heterogeneity, moderator analysis was performed on five possible moderator variables. The results of moderator analysis revealed that the impact of context-based learning on academic achievement was only moderated by group size. Specifically, studies with fewer than 50 participants demonstrated a strong effect (g=1.116), as did studies with 50-100 participants (g=1.096). On the other hand, studies with more than 100 participants exhibited a modest effect (g=0.498). These findings suggest that group size plays a role in moderating the effects of context-based learning on academic achievement. It implies that smaller groups may provide a more conducive environment for implementing context-based learning approaches, resulting in stronger effects compared to larger groups.