What does "service" mean?

On Friday, December 19, all of Chaska Middle School West was in the gym for a wonderful music concert - 7th & 8th grade bands, choirs, and orchestra. After the concert, I stayed to help clean up so PE classes could start. My heart dropped when I found smashed KitKat bars among the other trash on the floor. I also found packaging from one of the gift-exchange items that we had just shared in advisory.
Why did this disturb me so much? I guess because we have been trying to establish some expectations in advisory about how people should treat other people. Basic, common courtesy involves cleaning up your own messes (or perhaps not creating them in the first place). So here it is Christmas Eve morning and I don't want to forget to communicate with you about this. I realize that it was probably just a few people (and I'm NOT looking for names of culprits!) and that most of the 31 of you would not carelessly toss your trash on the floor (or smash candy bars that had been given to you).
What do you think? What does service mean to you? I'm glad that I was the one to clean up the mess, and not one of the PE teachers. What's in your heart, and do you think about the impact of your actions on others? Work for good, not for ill.