In order to teach, you must understand

I was talking to several of my fellow students before Christmas about the courses on offer at SMO, Scotland's only college offering degrees through the medium of Gaelic, and in particular the lost opportunity to teach languages efficiently to a completely bilingual student body -- an opportunity that no other higher education institution in the country has.

The only foreign language course currently offered is a single 15-point module in Irish, and this isn't offered until 3rd year.  Now one person said that it had been raised before, and it had been asked why Welsh never found its way onto the syllabus.  Apparently the college feels it isn't similar enough to Gaelic to be worth doing.  OK, there aren't many cognates between the two languages and those that there are aren't exactly transparent, but similarity can go much deeper than mere transparency.  In fact, from an academic point of view, it's the less visible similarities that inform most.

I've been trying to improve my Welsh recently, and while doing so I've been looking for academically interesting issues, and one I found was in the adjectives.

In Gaelic, the most common adjective ending is -ACH.  In Welsh, adjectives usually end in a vowel followed by G.  Different?  Not as much as you'd think.  CH in Gaelic is a C modified by a process called "lenition" in all the literature.  Lenition is the weakening of a consonant.  There's a process of lenition in Welsh too, although it's called the "soft mutation" in Welsh learning literature.  Guess what C becomes under soft mutation...?  Yup, it's G.  So even though the end result looks markedly different, on a process level, it's identical.

Teaching in this way (in either direction)  may make the new language seem a little less arbitrary.  But more than that, it also takes a single case that covers many examples and encourages an intuitive sense of equivalences across the languages, because it teaches you to accept unconsciously that Welsh G is often Gaelic CH and vice-versa. Thinking in terms of lenition as a process may also help students cope with examples that are lenited in one language and not the other.  It opens up a framework of possibilities, and if we are open to more possibilities, we're more likely to understand new and unknown language.

But in order to do this, the teacher must understand the material at a far deeper level than they're intending to teach.  You cannot simply spend your career one lesson ahead of your students in the textbook, because you have to know more about the subject than the textbook teaches.

The teacher needs to know a fair bit about the history and science that explains the development the language, even if he isn't going to talk about history or linguistic processes in class.

To give another example, it helps to know that the O->UE and E->IE changes in Spanish (eg poder->puedo, tener->tiene) are to do with Latin long and short vowels.  Now I'm not sure, but I believe the words that undergo this change had short vowels in Latin, and the ones that never change had long vowels in Latin, but it might be the other way round.  I don't need to know for sure, because I'm not going to teach this in class.  But I understand the mechanism, which at the very least means I won't waste time looking for a non-existent pattern in the Spanish. ( Or more correctly, I've stopped looking for a non-existant pattern in the Spanish, because until I was told about Latin, everyone told me "it's irregular" and I didn't believe it could be.)

Also, while many books will present this as a feature of irregular verbs, I now know that it's no such thing -- in reality it's a fairly regular and productive phonetic feature.  If you look at morphemes that can occur in multiple positions this same change occurs, and it happens for nouns, adjectives and adverbs as well as verbs.

The nouns "puerta" and "portal" share a root, and the latter retains the monophthong O simply because it's not in the stressed syllable.
An accountant (contable) works with accounts (cuentas) and again we see the change in action.

If we teach the vowel change as an irregular verb feature, the student won't necessarily be able to make the link between puerto and portal, or contable and cuenta -- the student won't have an understanding that imitates the intuition of the native speaker.  One morpheme will end up being considered as two, and the learner will find it more difficult to learn vocabulary or to devine the meaning of new vocabulary on first encounter.

Knowing the background allows us to identify the important distinctions that we need to present to our students, and that's a very good thing.

As a teacher, I am aware that always-O and unstressed-O-stressed-UE are different phonemes which share certain allophones.  This knowledge isn't explicitly required by my students (I'm a language teacher, not a linguistics professor) but it certainly must be known by them implicitly if they are to have a natural understanding of the language.

How can we do this? 

The obvious place to start would be with a couple of common verbs.  Poder and tener are very frequent, very useful, and a traditional place to start.

We have to make it clear what phoneme the student is using, and the O and E phonemes are never unambiguous in an unstressed position, so when we teach new vocabulary, we should pick a word that places the O or E in the stressed position -- so we teach "cuenta" before "contable".  We make comment on the fact that cuent/contable share a morpheme (but we don't need the word "morpheme", because everyone's happy with the word "root") and that therefore it follows the same rule as verbs -- it's diphthongised in the tonic syllable and a monophthong elsewhere (although we can follow Michel Thomas's lead and replace the technical talk with the idea that the vowels "break under stress").

But plainly and simply, the student must have an implicit understanding of what's happening, or everything becomes arbitrary and meaningless, hence difficult to learn.