Ted,
Sounds like you've "been through it all". Responsible students will usually yield to the first or follow up suggestion their behavior is out of line. One on one visits after class may be needed. I have students sign a document, much like a contract that states my expectations, consequences for further occurrences, and the student's acknowledgement. Of course, they usually don't like this, but I rest in it's not me, but the student who is out of order.
Barry Westling
