one mole of marbles would cover the earth to a depth of 50 miles

An example of quotidian comparisons for a scientific concept*:

"Analogies for Avogadro's Number

The immensity of Avogadro's Number (A_N) is so great that it is impossible for a person to have a true realization or comprehension of just how large it is. As a result, analogies are used to try to get some idea of its size.

This group of analogies are examples of typical textbook analogies:

a) A_N of marbles spread over the surface of the earth, would produce a layer of marbles about 50 miles thick.

b) A_N of grains of sand spread over the United States, would produce a layer of sand about 3 inches deep.

c) It would take 3 million years for the world's entire population of 6.5 billion people, counting at the rate of one object per second, to collectively count an Avogadro's Number of objects."

Previously posted at scienceanalogies.com by retired science teacher Murray Hart – original source: Poskozim,P., Wazorick,J., Tiempetpaisal,P., and Poskozim, J. Analogies for Avogadro's Number Journal of Chemical Education 1986, 63(2), p.125.

Although Avogadra's number is a number, the concept of 'Avogadra's number' is not defined numerically (like a dozen or a score), but (conceptually) through the relationship between a mole of some entity (molecule, ion, electron…) and the number of those entities.

Read about analogy in science

Read examples of scientific analogies

These are analogies, as suggested in the quote, but I am classing them with other examples of 'quotidian comparisons' which offer commonplace comparisons to make sense of extreme scales or measures.

Read examples of quotidian comparisons