What's Fair?

We intended to talk about how the intentions of the day before panned out throughout the day and ended up talking about what was fair in regard to consequences.  With students consistently leaving supplies laying around and not picking up after themselves, we told them that for every pencil that was left on the floor after morning meeting, a tally would be given for the entire class.  They voiced that that was not fair.  We asked them if it was fair to expect us (the teachers) to pick up supplies that they borrowed, used, and left on the floor.  They responded: no.  This led to a conversation about how change in behavior can happen any number of ways, but ultimately, in any species, change happens when conditions get to a point that they are no longer willing to tolerate