I used to teach middle school, so I sort of know your audience. Sort of, as families and kids can all be so different! My first thought, and one that may not be any good, was to have a portable design wall and fabric pieces on it that hadn't been sewn together, offering different patterns...or maybe some blocks sewn together but the final design hasn't been decided.
Or maybe be trying to decide what fabrics to use for a pattern, while having a few completed quilts "up for show." Or auditioning different ideas for a border of a top that has been almost finished. Not sure if you are after audience participation or not...
Our librarian used to have a quilt club, and I was always surprised at how many students she got interested in the hobby. She always had two or three quilts on display in the library, plus one that the students could make if they were part of the club. I wasn't a quilter then, so I really don't know how it worked. Don't even know if it was after school or anything.
Yearbook sponsor... been there done that! You are one busy lady, and I know you will get more suggestions...
Dina