This study explores the effectiveness of online discussion forums in enhancing student learning by proposing and empirically testing a conceptual model based on the "theory of online learning" and "media richness theory." The research extends media richness theory by suggesting that using multiple media types can improve communication and perceived learning. Hierarchical regression analysis revealed that the perceived richness of online discussion forums positively impacts student participation, interaction, and learning, especially when combined with traditional classroom lectures. The findings offer valuable insights and guidelines for educators on integrating online forums with classroom instruction.