This quasi-experimental study examined the impact of structured instructor postings on the participation and performance of student discussion groups in a blended classroom. Undergraduate students enrolled in an instructional technology course were assigned to either a treatment (instructor postings; n=97) or control group (no instructor postings; n=98) for three distinct discussion topics spanning a six-week period. A crossover design was used to control for timing and instructor biases. Resulting student posts from all three discussions were compared between the groups with respect to quality and frequency. Quality of student discussion posts was determined based on an assessment scoring rubric, while frequency was measured in terms of the number of student posts. Results indicated that instructor posting did not impact the quality of student posts but did negatively correlate with student participation as measured by the frequency of their posts. These findings suggested that although students received equal quality scores in both situations, different posting strategies were utilized in the presence or absence of instructor posts. Further research is needed to explore specific strategies students employ when posting with and without instructor intervention, and to consider how this knowledge can be used by instructors to support students in online discussions.