Object: A little sponge toy that expands in water (can be found in most toy and novelty shops) and a pan of water. Might want to buy two or three and experiment with them to discover how long they take to expand.

Good morning, boys and girls. I've got the coolest thing to show you this morning. It's called a sponge toy. What do you think? Doesn't it look like fun? No, I guess it doesn't look very fun, does it. It's so little that you can't do much with it. But look what happens when I put the sponge toy in water. …