In this day and age, nothing surprises me.The question also hinges on the nationality and age of the questioner. A common 5.25" floppy is about 13 cm in size. Perhaps the young teacher didn't have his units correct.
People often don't believe me when I tell them that the floppy disc actually hails back to the 1950s. But it does and was not used for digital recording.
--Chuck
