When I taught a community quilt class open to the public I had a big sign that had Do's and Don'ts for the class members. I had to be very specific as in Do not ask to borrow from other class members, ask instructor for what you need. It was the only way I could corral every type person that showed up. I wish the instructor gave out a Do and Don't list with the class ad. Most don't need it but it only takes one to ruin the class for someone.