So, i had considered curving the participation portion of the grade in my class this semester, but when the distribution looks like this, i don’t really (a) know what curve strategy would have a “desired” effect or (b) have much sympathy for the students’ (lack of) effort. Suggestions? 
Permutations
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Permutations 
Are the no-shows binned in the lowest bin? Can you try splitting up the bins into smaller increments to find a (nominal) peak?
At least in this context, if it ain’t Gaussian, then I’d be suspicious of your measurement/reporting methodology.
i actually dropped the no-shows from that particular graph. And while i understand your point about the distribution (i might have mentioned initially there is a strong small-N problem at work here), actually this genuinely reflects my perception of their individual efforts in the class. Also, my calculation of participation points is really clearly stated in the syllabus, updated regularly and has numerous ways to earn (more than) full credit for this portion of the grade. Further, it is a strategy i have used successfully several times in other classes. All that to say, i actually am fairly comfortable with how they broke out and would feel absolutely comfortable leaving that portion of their grade as is. i’m just curious – if i were to go super-softy on them for this – if anyone had recommended strategies.