One attention-getting activity is to make a spoon sing. It can be used to show both sublimation and gas pressure. An ordinary metal spoon is warmed above a flame for a minute or two. The spoon is then pressed firmly against a chunk of dry ice which is held by someone wearing gloves and using insulated tongs.
The dry ice quickly sublimates when touching the warm spoon --- the carbon dioxide bubbles out but is blocked by the spoon surface. The gas pressure will force the spoon away a slight amount allowing some gas to escape, then the pressure of the person's hand pulls it back onto the ice. This process repeats rapidly, so the spoon vibrates and makes noise much like a tuning fork or teapot.