Irritable vowel syndrome

This is the sort of thing that makes my head hurt.

This morning while looking through some old files I came across a "language arts" exam given to middle school students in Carriacou (Grenada) in 1983.  The very first question:

Put a ring around the word that has two vowels
(a)  man     (b)  pet     (c)  gram     (d)  boat

Okay, now, we all know what the expected "right" answer was, don't we?  Of course.  It was (d) boat.  Because the word boat has two vowels.  Except that it doesn't, really.  The word boat, pronounced in Grenada as [bot], has one vowel (some speakers produce something like [bʷot] with a very brief labiovelar glide- still not two vowels, though).  The oa spelling of this vowel is an artifact of the convoluted history of the English writing system, not an accurate reflection of the present underlying phonology of English.

Of course, what's going on here is the perpetuation of the ancient language = writing meme, by which any question about language is assumed to refer to the writing system, not the actual spoken language.  Indeed, here in the US of A young people spend their K–college years attending "language arts" and "composition" classes that almost universally focus on writing (spelling, punctuation, etc.), not language.

Anyway, that was 1983.  My head is hurting now because yesterday, in a guest lecture on language, I asked the 100+ students in the lecture hall how many vowels are there in English?  And after all these roughly 25 years of teaching about language, the question still works: they still fall into the language = writing trap.  Their universal answer: five, maybe 6 (a, e, i, o, u, sometimes y).  I then astounded them by pulling out my twelve vowel sounds, as in the following words:

beat                     loot
bit        bird         look
bait                     coat
bet       bud         caught
bat                      cot

A part of me enjoys tricking students in this way, semester after semester.  And it's so predictable.  But another part of me bemoans the fact that I can still do it so easily.  Students in the English-speaking world simply do not, apparently, receive substantive instruction on the nature of language, or the nature of English.

Will they ever?