Fire Ants: Just Floating Along

Imported Fire Ants March 08, 2013 Print Friendly and PDF

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Activity: Just Floating Along

Hands-on Exercise:

Try this experiment to see why ships needed "ballast." This activity will demonstrate the need for "ballast" in the "hold" of a ship to maintain the ship in an upright position as it travels the seas from port to port.


  • Plastic 1-liter soft drink bottles, or plastic toy boats if desired
  • Sturdy scissors that can cut through the plastic bottles
  • Containers (large enough that the plastic bottles will fit into lengthwise) filled with water
  • Plastic sandwich bags filled with soil, sand or rocks (make the filled plastic bags of various weights)


  1. Cut the plastic bottles in half lengthwise to resemble a boat.
  2. Place the plastic bottles into the containers filled with water.
  3. Observe how the plastic bottle floats.
  4. Place a filled sandwich bag (“ballast”) into the center of the bottle.
  5. Observe how the bottle floats.
  6. Place more bags into the bottle until it sinks, making observations on how the bottle floats.

Questions to answer

  • Does the bottle sit evenly or unevenly in the water?
  • Does adding the filled sandwich bag stabilize the bottle so it floats better?
  • Does it matter where you place the sandwich bag in the plastic container? Front? Middle? Back?
  • What happens when you place too many bags in the plastic bottle?

Teacher version

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