What is the fix, and what is the win?
Is to use diaeresis to help teach a short list of words, like "coop", in order to distinguish between two pronunciation forms ("We bought the chicken coop at the farm coöp.")?
If so, that specific form can be fixed by writing it "co-op". How many other words are in that category at the elementary school level, and how many can be addressed by using a '-' instead of a diaeresis?
As it is, elementary school teachers already need to teach that 'lead glass' and 'lead the way' are different; and how some words like 'read' change pronunciation in the present and past tense but are spelled the same. So it's not like there's much of a fix to have a handful of words with a diaeresis.
If we change to use diaeresis, what other words will need to be changed in to fit the rule?
Don't jeer at the seër. (Most "ee" words have a long e ("seed", "seem", "seen").)
I'm a top tier square knot tiër.
I am so good at peeing I am a peër without peer.
Just like cooperative might be shortened to co-op or coop, coaxial cable might be shorted to co-ax or to coax. https://en.wikipedia.org/wiki/Coaxial_cable uses all three! But if we teach diaeresis, then we'll have a third spelling -- coäx.
I could go on. My point is, the diaeresis rule isn't that easy to explain to elementary school students.
By comparison, teachers already use syllabification (see https://en.wikipedia.org/wiki/Syllabification ), which naturally extends to these cases where diaeresis might help!. Quoting that Wikipedia entry:
> The written separation into syllables is usually marked by a hyphen when using English orthography (e.g., syl-la-ble) and with a period when transcribing the actually spoken syllables in the International Phonetic Alphabet (IPA) (e.g., [ˈsɪl.ə.bᵊɫ]). For presentation purposes, typographers may use an interpunct (Unicode character U+00B7, e.g., syl·la·ble), a special-purpose "hyphenation point" (U+2027, e.g., syl‧la‧ble), or a space (e.g., syl la ble).
So, when teaching, write "co‧op" and "pe‧er" and "se‧er" and "co‧ax". I think that's what my primary school used.
This doesn't even require fancy Unicode interpuncts - hyphens also work. That's the "co-op" solution I mentioned earlier. Only, it can be applied to every multi-syllabic word.
You can see examples (if you have an archive.org account) of hyphens used in teaching syllables at https://archive.org/details/teachingphonicsf02edstar/page/90... .
FWIW, here's a 1852 book using acute accents to indicate stress, which teaching elementary English grammar - https://archive.org/details/anelementaryeng00lathgoog/page/n... .