Campers used film canisters and Alka Seltzer to create their film can rockets. First, they put a sticker of a shuttle on their can, upside down. Next, they filled the can 1/2 full with water. They dropped a seltzer tablet into the water, replaced the lid, gave it a shake and placed it lid side down on the ground. Wow, do these shoot up high!!!  My brother is an expert and volunteered to be in charge of this event.