Floater / Sinkers - Archimedes Principle
    Buoyancy-
 Buoyant force acts in the upward direction, against the force of gravity so it makes an object “feel” lighter.

    Archimedes
        One day, while getting into his bath he noticed water spilling over the sides. In a flash, Archimedes realized the relation between the water that had fallen out and the weight of his body - in other words he discovered why some objects float and some sink! Archimedes was so excited with his discovery that he hopped out of the bath, and rushed naked into the street yelling triumphantly, 'Eureka!' 'Eureka!' (Greek word for      'I have found it!).

    Archimedes Principle
        buoyant force on an object is equal to the weight of the fluid displaced by the object.

Submarines: How They Work – Archimedes' Principle

    http://www.onr.navy.mil/focus/blowballast/sub/work2.htm
            what happens to the hull to allow the submarine to submerge?
 

The Archimedes Principle is based on density
            what is density?  Can you tell which one is more dense?

        Layers of Liquid
                http://www.hazelwood.k12.mo.us/~grichert/explore/dswmedia/density.htm

        What makes up density?
        
Both cans say 12 fl. oz. (fluid ounces) or 355 mL.
appear to be the same size and weight so should have the same density.
Density Comparison to Water:
    the density of many substances is compared to the density of water.
      Does an object float on water or sink in the water?
                Compare the information on the cans