I would use double tacky ATG (Adhesive Transfer Gum) to hang student artworks
on the cafeteria tile and brick walls. It like a double sided tape (but it
is just the sticky stuff, no paper) that is typically used in picture
framing. It's not that expensive and is extremely durable. And it can be
removed from the back of art work with rubber cement pick up. You can get it
in most catalogs and good art supply stores.