Learn all about buoyancy and Archimedes’ principle with the Jellyfish Cartesian Diver. Teach your kiddos basic science with this Heebie Jeebies Jellyfish Diver! Children ages 3 and up with adult supervision can learn about buoyancy and Archimedes principle with this cartesian experiment. Simply pour water into a plastic bottle, place the colorful jellyfish toy inside, and close the lid. Next show students how to squeeze the bottle to get the jellyfish to float up and down and even spin.