This study used the Community of Inquiry (CoI) model proposed by Garrison to investigate students' level of knowledge construction in asynchronous discussions. The participants included 36 senior students (27 males) majoring in information management. The students attended 18 weeks of an online information ethics course. In this study, four types of discussion topics--theory exploration, life experience, case-based, and debate discussion--were designated, and their relationships with cognitive, social, and teaching presence (CP, SP, and TP, respectively) were explored. The students' attitudes toward and perception of online discourse were also examined. Data were collected from the participants' message posts, the teacher's reflection notes, and a survey that the students completed. Content analysis was performed according to the CoI model. The results indicate that the discussion types were significantly related to CP, SP, and the students' perceptions of the course, but that the discussion types were not related to TP. This study also found that the students' level of knowledge construction was best for topics related to life experience and case-study analysis. Therefore, this study recommends that to enhance the students' level of knowledge construction, teachers should design case-based discussions that are combined with social events or life experiences that integrate authentic aspects of personal life rather than pure theory or debate issues.