If you walk into a room with 8 children and it happens to be a disaster, who made the mess? You could play detective, I know you all want to be Poirot. This one doesn't take much detective work though, you only need to think like a child. See "THE MESS" no one made. Not one of the kids went in there and threw blocks all over the floor and made crumbs from their toast or threw papers around. The key word here being 'One'.
What happened is that one child played with the blocks, and another got crumbs on the floor and yet another threw their papers on the floor, probably on accident but they didn't fix their accident. The combined effect was a very messy living room. And no one is gonna claim responsibility for the whole mess. Oh sure its a great teaching opportunity about how taking responsibility for one's self can eliminate a mess. If everyone had taken care of what they had there would be no mess. With the grand overview being how society would be better off, blah blah blah. You could turn it in to a math lesson, about how a whole mess can be made into 3 equally messy incidents. Heck you could probably even teach art with the colors of the blocks and the texture of the crumbs. But mostly we just want the room cleaned up. And that is a whole nother problem.