Participants turn eggs into submarines to experiment with neutral buoyancy!
- Three aluminum roasting pans
- One bucket
- One plastic drop cloth
- One roll of duct tape
- Two packages of non-soluble, oven-bake clay
- One roll of paper towels
- Three plastic containers
- Three plastic eggs
- One pair of scissors
- A handful each of foam peanuts, paperclips, pony beads and washers (used to weigh down the plastic eggs)
Preparation (An adult should handle each of the following steps)
- Cover a table with a plastic drop cloth.
- Fill three clear plastic containers approximately three-quarters full of water.
- Place each container in an aluminum roasting pan to protect the activity table from water overflow.
- Place each container and pan an equal distance apart to create three walk-up stations.
- Fill one bucket approximately halfway with water and be prepared to add water to the containers as participants work with their plastic eggs.
- Divide two packages of non-soluble, oven-bake clay into quarters.
- Use small pieces of duct tape to cover any holes on the eggs.
- Place one egg in each pan.
- Place remaining materials on the table.
At-Home or In-Classroom Instructions
- Have children work at a station with a water-filled container inside of an aluminum roasting pan.
- Explain that they will create a neutrally buoyant egg-marine (plastic egg submarine) and that when an egg-marine is suspended in water, it is neutrally buoyant. Neutral buoyancy occurs when the mass of the egg equals the mass it’s displacing or pushing out of the way. This offsets the force of gravity that would otherwise cause the egg to sink.
- Tell children that to achieve neutral buoyancy, their egg-marines cannot sink and touch the bottom of the container or have any part floating above the water. The egg-marines must remain suspended in the water for at least 10 seconds.
- Explain that children may only use one piece of pre-cut clay.
- Explain that participants can add or remove weight by filling their eggs with different objects (e.g., foam peanuts, paperclips, pony beads and washers) in various amounts.
- Have children create and test their egg-marines. As they work, ask them what they can do to stop their egg-marines from sinking to the bottom or floating to the top.
- Congratulate children when their egg-marines neither touch the bottom of the container nor break the surface of the water for at least 10 seconds.
What Are We Learning?
Scuba divers must achieve buoyancy control to explore the environment at certain depths, avoid crashing into coral reefs and other fragile marine life, and keep from going deeper or ascending faster than is safe. If divers do not control their buoyancy and ascend too quickly to the water’s surface, they risk getting decompression sickness that is commonly called “the bends.” Ascending too fast allows nitrogen gas to be released as bubbles, which can build up under the skin, tissues and joints, and against the spinal column. Divers control their buoyancy by stopping at certain points on their way back up to the surface and waiting for their lung pressure to adjust to their surroundings.