If this is a 6 hour workshop, you may want to go over a few things first with the group like keeping food water coffee away from the work area, assess the quilting abilities of the students so that you can group the less experienced ones together, maybe keeping cell phones off when you are teaching but can be on while they are sewing etc. I like to have 6 to 10 people in a class. That is just my personal preference as I don't like to be in larger groups.