Chantel,For large classes,( though I have to say 18 is small for me, 24-30 is the norm)I would suggest hooking up an Elmo, a camera hooked to an LCD projector. You demonstrate under the camera and it projects up on a large screen for all to see. We also have small sketch activities at the beginning of class and I find having half the students work on the sketch activity and demonstrating to the other half, then flipping works too.
Middle School Art Instructor
I have a class of 18 eighth graders. I am teaching them watercolor and would like to do some demonstrations. Any suggestions of how to keep half of them occupied while about half watch the demo? I have a few rowdy kids in there, so they definitely need to be occupied. I would love to be able to demonstrate to all at once, but haven't figured out how to make that work.