Graham, Students do pick up on cues from their instructor regarding what is acceptable or unacceptable behavior. I have several carpeted classrooms that are very nice, very comfortable. Only bottled water is allowed in these classrooms. To some students, not having an open (or closed) cup of coffee at their table is a foreign idea, so I'll reinforce the classroom rule by taking a sip of water and saying something like, "Boy, a cup of coffee would sure be nice but like you guys, I have to follow the rules too". Barry Westling