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A cruise ship in the bath tub or plastic tub?

Rolling along the high seas with Rubber Ducky? Why not? Especially if you can learn some scientific lessons along the way. Here is a fun project that satisfies both the seafarer and investigator in any kid.

• 1 solid wood building block
• 1 plastic cap from a bottle
• 2 pieces of aluminum foil
• 1 chunk of clay
• 1 pair of pliers
• bathtub (or sink) filled with water

1. Hold the wood block in one hand and the plastic cap in the other hand.
2. Which one feels heavier?
3. Do you think the wooden block will float, or will it sink?
4. Will the plastic cap float, or sink?
5. Put both of them on the water to test your predictions. What happens?
6. Put both of them under the water. What happens now?
7. Take a piece of aluminum foil and squeeze it into a solid ball with the pliers. Drop it in the water. Does it float or sink?
8. Get another piece the same size and shape it into a little boat. Place it on top of the water. Does it float now?
9. Try the same experiment with clay. Make a ball and drop it in the water. What happens?
10. Shape the clay into a boat and put it on the water. Does it float now?

What is happening?

The clay and foil balls sink because they are squeezed into small shapes, and only a small amount of water is trying to hold up the weight. When you spread out the clay or foil, it floats because the weight is supported by a lot more water.