I had a 5th grade group that had trouble coming in noisy, and wouldn't quiet down once they were in the room. I made them line up in the hall and practice coming in quietly, over and over and over until they finally managed to do it. It wasted most of their art time, but it seemed to help. We didn't have to do that the next week. (Unfortunately this approach didn't work at all with my 8th graders, 2/3's of the way through the year and I'm finally starting to get some work out of them!!)