However, what makes more sense to me is a comment I found in James Turney Allen's "First Year of Greek": (published 1917) that the grave
Following this reasoning, for those who use the accents as now indicating "stress" rather than "pitch", we should probably not put stress on a grave, nor drop the pitch below the normal level."is merely a sign to indicate that a syllable which would normally be pronounced with the rising inflection (acute) is not so pronounced, but that the voice remains at the monotone level."
I'd be interested to hear how others present accents to their students.