Each can has a number of variables that can be discussed
and experimentally investigated, for example, the amount of
liquid in the can, the amount of gas above the liquid, the pressure
of that gas, the size and shape of the can, the density of
the liquid in the can, etc. A valuable student discussion might
include the likelihood that these or other variables might
contribute to the observations. Students might make “cans”
from their own materials (e.g., bottle, jars) and test the effect
of these variables on density and buoyancy.