A layman's question: one of the first things I learnt when beginning with Gaelic was that the n in an changes to m before b, f, m, p. Was it rote learning (because I wasn't told why these particular four) or meaningful learning (because it constituted a rule)?I told him that this is rote learning, because he's simply learned a list of letters and a mechanical rule. But there is a more meaningful way to learn this, which makes it an excellent example to work through to demonstrate my point. I'll use a bit of linguistics terminology, but I'll try to make sure that I make the meanings clear as I go. Remember, though, that just because I'm using it here, doesn't mean I'm advocating its use in the classroom.
To make a rule meaningful, there has to be structure round about it that makes automatic sense to the learner. Logic's good, but logic neither guarantees nor is necessary for something to be meaningful. (In fact, my Dad used to quote one of his lecturers all the time: people don't think logically, they think psychologically.)
The key to making it meaningful is tying it into a network of easily-understood relationships. (And sometimes the thing that's easy to remember isn't altogether logical.)
In order to work out a meaningful teaching strategy, you need to analyse the material to be taught.
In this case we have a fairly simple rule:
"An" becomes "am" before words starting with B, F, M or P.(The complication is that "an" is actually several different words, but we'll skip over that for now.)
What are the special properties of these four letters?
B, F, M and P are labial consonants, ie. they are pronounced using the lips. In fact hey are the only labial consonants in Gaelic.
M and N are nasal consonants, and are very closely related, as they're nasal consonants. It's not particularly easy to switch from N to a labial consonant, so the N steals the labial quality of the following consonant and becomes an M.
The technical rule:
The unstressed clitic forms "an" become "am" before a labial consonant.
So we have a full linguistic description of what's going on. If you say that this isn't "meaningful", you're right -- only a trained linguist would be able to make use of this information. It's the teacher's job to turn this technical knowledge into something meaningful -- but the teacher needs to understand this technical rule before he can teach it.
The next thing is to look for something similar that the student already knows.
Let's have a look at how N behaves in English.
The prefix in- is used for negatives. We know these are negative and we know they're N.
Admissable - Inadmissable
Tractable - Intractable
We know this.
But what happens when we want to add it to a word starting with B, M or P?
Balance - Imbalance
Material - Immaterial
Possible - Impossible
This doesn't just happen with negatives. The opposite of ex- is also in-
External - Internal
...which also changes to M:
Explicit - Implicit.
So the students now know that N changed to M before B, M and P. You can now explain that it's because these consonants are pronounced with the lips (or you can get the students to notice that for themselves). Now the Gaelic rule is no longer strange and arbitrary, but quite familiar and comfortable.
(It might also pay to point out that while you might see words that appear to break this rule in the written form, they tend to follow it in pronunciation -- eg input.)
This only leaves F as a troublesome case, but seeing as your students are now aware of the notion of a labial consonant (although you've never used the word "labial") you can just point out that while B, M and P use both lips (ie they are bilabial), F uses one lip and your teeth (called labio-dental). As it's only using one lip it's a borderline case. Some languages bundle it with B, M and P, others with the rest of the consonants. Gaelic's one of the former. Shrug and move on. It makes sense, and it doesn't pay to think about it.
Yes, there is an element of "smoke and mirrors" here. But some people have a tendency to overthink things and start to question things that don't need questioning. Write it down as a formal rule and people will analyse and question it. If instead you present it quickly as natural, if you don't encourage thinking, people will accept this, and that's good.
Now that may seem a much longer way than "an becomes am before B, F, P or M", but taking five minutes to make sure people understand it means you're not going to spend as much time revising it later. Less haste, more speed.
However, you can do more than make this one rule meaningful -- you can also prepare the student to learn later parts of the language meaningfully.
The concept of N taking on a labial quality is analogous to several other changes in the language -- the student needs to be aware that sounds affect each other. For example, in a phrase like an comhnaidh, the C starts to sound like an English G, because the voiced nature of the N affects the C. The O becomes a nasal vowel, due to the influence of MH. In many dialects, the C has an effect on the preceding N, too. Just like how English ink is pronounced like ingk because of the effect of the NK combination, and how engage is often pronounced eng-gage rather than en-gage, the N picks up an "ng" quality -- an becomes ang.
As this sound "spreading" is an important and productive feature of the language, bringing it in early makes it all easier later on.
Also, you can help your students understand related sounds better. In my example, B, M and P were presented separately from F, echoing the distinction between the bilabials and the labio-dental. We can go one step further, and rearrange BMP to something else. I would advise putting B and P together because they're both plosives, ie they have a "pop" involved (thing explosion). Now we have a choice: do we stick B and M next to each other? Both are voiced, so it would make sense. Now we have MBP or PBM, rather than the alphabetical BMP. We're building associations that can be built on later, and we're subtely drawing attention to something the student really already knows, at a fundamental level. Which brings us to the core point of meaningful learning: it must be built on what the student already knows.