At the core of most Learning Management Systems is the discussion board. It is not uncommon to average 100 posts per student in a semester class (20 students = 2,500 posts including instructor). The discussion board is where "the rubber hits the road".
Remarkably, when we asked a sampling of our online students what made their online classes special, most responded "everyone is heard" - it is not just the students in the front row, or the ones with the quick answer, or the teacher's pet. Every student posting in response to the common weekly discussion question is read and responded to by the instructor.
This link includes a rubric matrix for grading discussion posts.