In Metric, one millilitre of water occupies 1 cubic centimetre, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade - Which is one percent of the difference between its freezing and its boiling point. An amount of hydrogen weighing the same amount has exactly one mole of atoms in it.

Whereas in the American system, the answer to "How much energy does it take to boil 1 gallon of room temperature water?" is "Go Fuck Yourself", because you can't directly relate any of those quantities

Discuss.

Lengths corresponding to arm length and walk stride are more relevant than whatever metric is based on.

Fahrenheit vs Celcius is great too

And wait until you get out into international waters and sail anywhere in the world. Distances in nautical miles (which are longer than land miles), speeds in knots, and comms in English.