The property of water that the students are testing is the density of water.
Upthrust or Buoyancy force, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object.
F = ρVg
where;
Thus, the property of water that the students are testing is density of water because it opposes the weight of the pennies dropped into it.
Learn more about density here: https://brainly.com/question/6838128
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