Here's what we did, we put three scoops of jiggly marbles into a test tube and placed in a rack. Then Jude added about 10 mls of water using the funnel. Over the next hour we watched in amazement these tiny balls expand. These marbles contain a super absorbent polymer, in fact bubble gum has a similar polymer that gives its elastic properties.
One of the neatest part of our experiment was that if you let the marbles sit out for a couple days the water will evaporate and they return to their original size!
