Coke vs Diet Coke

Students came into science class today to find a can of coke and a can of diet coke swimming in an otherwise empty fish tank.  We discussed and demonstrated why the coke sank to the bottom, while the diet coke floated to the surface.  It all has to do with their relative densities.  Since water has a density of 1 g/mL, any object with a density greater than 1 g/mL will sink in water.  All objects with a density less than 1 g/mL will sink in water.  Since both cans have the same volume (take up the same amount of space), the difference must be in their masses.  It turns out that coke has a mass that is 15 grams more than that of the diet coke.  That makes the coke more dense than the diet coke, and more dense than the water, causing it to sink.
We then used the student responders (in some classes) to take an online practice quiz on density mass and volume.  We ended class by doing an graphing exercise (all but 5th period) on plotting mass and volume.
Tomorrow we will cover graphing, our last topic of this chapter, more in depth.
There is no assigned homework, and the test is on Wednesday, September 30th.
Have fun at Ocean City, Maryland and Jamaica (you know who you are).