With the posting of course grades at the end of a term comes the opportunity to have conversations with some students about things that they might have overlooked earlier in the semester. Recently, Chris, Adam, and (somewhat) I were talking about one such example: the meaning of "class participation".
I'll stick to discussing my own experiences. Invariably, at least one student will express surprise at a low participation grade by pointing out, "But I attended every class meeting!" or "But I talked a lot!". In the syllabus, during the first weeks' class meetings, and occasionally throughout the semester, I emphasize that those behaviors are neither necessary nor sufficient for good participation (or for a good participation grade). Instead, I emphasize and evaluate other things as part of my conception of (constructive) participation.
For instance: do your comments demonstrate that you've done at least some of that day's readings? Do your comments build on others' comments in some (respectful) way? Do you sometimes refrain from commenting, knowing that sometimes, being a good participant in a discussion means letting other people talk? If you're too shy or anxious to talk during class, then do you use other means -- such as the class's discussion forum online -- to raise comments and questions that demonstrate your engagement with the readings/concepts?
Key to my participation assessments is a brief conversation with each student about their participation, at least two or three times during the semester. (Surprisingly, that doesn't always forestall the "but I talked a lot!" complaint at the course's end. Even more surprising is that I'm surprised.)
How do you assess/grade students' participation, if you do? How do you define "participation" in the first place?