An excellent student satisfies all of the following criteria. Do you:

Participation is one of the most subjective activities to assess. Hence, you should ask yourself: Am I consistently making a positive contribution and impression on the instructor and other students? I do consider if your peers recognize you as an (a) insightful contributor or (b) someone that seems unprepared or monopolizing in discussions.

I make my assessments based on mid-semester and final evaluation forms.