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Density & Buoyancy (Alcohol & Water) (Marissa Staller)


Marissa Staller

Principle(s) Illustrated

  1. Density is a physical property of a substance.
  2. The density of an object and the fluid in which it is in immersed can be used to predict whether the object will sink or float. 


  • 8.8.a. Students know that density is equal to mass per unit volume.
  • 8.8.d Students know how to predict whether an object will float or sink. 

Questioning Script

Prior knowledge & experience:

Students are used to seeing ice float in water. Because alcohol is less dense than ice, the ice will sink. This discrepant event will help them to question why objects sink and float.

Root question:

Why does an object float or sink? How can an object float in one liquid and not another?

Target response:

An object will float if it is less dense than the fluid with which it is immersed. 

Common Misconceptions:

Students may believe that whether an object will float or sink is dependent on its weight. "Heavy" objects are thought to sink, while lighter objects are thought to float. 

Photographs and Movies

Put all photos in the class Picasa Album and reference here.  Do not upload the photos directly to this wiki as there is not enough memory in the website.

Put all movies in your own Youtube account.  Make sure that the account is set for public viewing. Insert the Youtube videos here. 


5E Model Lesson on Density & Buoyancy -