The present study sought to investigate how to enhance students' well- and ill-structured problem-solving skills and increase productive engagement in computer-mediated communication with the assistance of external prompts, namely procedural and reflection. Thirty-three graduate students were randomly assigned to two conditions: procedural and reflection groups. Pre-/post-experiment design was conducted to examine differences in problem-solving processes, particularly in problem representation, solution development, justifications, and monitoring and evaluating. Students initially formulated individual responses to well- and ill-structured problems with the assistance of procedural or reflection prompts, and later discussed their solutions with assigned group members within CMC. The results demonstrated that students received reflection prompts performed better in making justifications, monitoring and evaluating the plan of action for the ill-structured problem than those received procedural prompts. Additionally, the results of content analysis showed that reflection prompts served a critical role in fostering the use of higher-level cognitive skills such as reflection and reasoning and for facilitating learners' reflective practices in online group discussion. This study suggests the use of question strategies and task complexities should be carefully implemented so the quality of CMC learning can be ensured.