how can is happen that three different animals could be claimed largest?

Question

Describe how it could happen that three different animals could each be claimed -rightfully- to be the largest of the three. Discuss the implications of this kind of situation for teaching students about measurement. 

Answer 1

The tallest animal can be said to be the largest, and the claim verified with linear measurement using a tape measure. (The same can be said for the longest.)

 

The heaviest animal can be said to be largest, and the claim verified by weight using a scale.

 

Weight does not always correspond directly to volume.  Birds are light for their volume relative to terrestrial animals.  To test the volumetric claim, fill a dunk tank.  (Briefly) immerse each animal in the tank and capture the overflow.  Measure the volume of the overflow which, by the property of displacement, will exactly equal the volume of each animal.  (If it is necessary that the lab assistant get his hands in the tank, he should take care to measure how much of his hands were immersed each time, so he can eliminate his contribution from the calculation.  Gloves are marked, tank refilled, hands reinserted to mark, overflow captured and measured.)

 

(Obviously the last measurement is easiest to make if the specimens are dead.)

 

Care must be used in defining the terms of a question.  Common language and casual usage are not appropriate in an experimental setting.  The term "large" is not specific enough; "Tallest", "longest", "heaviest", and "greatest volume" are all specific enough to be tested.

 

Additional complications can be introduced into the problem.  Do tails count?  If a dog has a curled tail, does one straighten the tail before measurement?  What about feathers?  If one feather is sticking up does that add to the height?  

 

In any experimental situation you want to define your terms before you begin your measurements.