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Properties: Sink or FLOAT!

What was the point of this activity?

  • To help students understand and visualize how density affects whether an object floats or sinks in water.

Explain how you would introduce this to your class?

  • Explain density and describe that the density of water is 1g/ cm^3
  • Allow students to make a hypothesis whether the objects will float or sink
  • Introduce hands-on activities and observing by placing each object in the water to see if our hypothesis is correct or incorrect.

Where do you see a student having difficulty with this?

  • Size doesn’t matter whether an object will sink or float. For example, a tall container with a steel cylinder will float because the bigger container has more air and is less dense. Density doesn’t change because¬†of the size of the item. Confusion about the Pepsi is sinking while the Diet Pepsi is floating.

What changes or extensions could you do to this activity?

  • Allow students to bring two objects from home that they believe will sink or float and test their hypothesis.

Scientific Principle:

Water has a density of 1g/cm^3. If an object is over 1g/cm^3, the object will most likely sink in the water whereas if the object is less than 1g, it will float above water. In the images above, the Pepsi can sunken to the bottom while the Diet Pepsi is still floating. The Diet Pepsi contains an artificial sweetener, Splenda, making the can lighter than the Pepsi can. Pepsi different ingredients such as real sugar and corn syrup which makes this can denser.

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