This is not to say that I have lost all faith in the notion of order in acquisition. My own efforts to uncover such an order among the Taiwanese I work with will rely on the principle of stratification. In geology and archeology, the stratification principle simply states that, unless disturbed, the longer something lies around, the deeper down it will lie. I expect to be able to apply the principle to language acquisition in the following way.

Given that any group of learner/acquirers will exhibit disparate levels of learning and acquisition, and assuming that all learner/acquirers, or all learner/acquirers of a certain background, tend to acquire (if not learn) language items (specifically functors, or grammatical morphemes) in a certain order, analysis and comparison of the language items acquired by individual learner/acquirers will reveal a tendency for items to stack, such that all learner/acquirers of a certain level will be found to have acquired the same items, and comparison of two only slightly different levels of acquisition should reveal the item or cluster of items that falls next in the series.

Krashen explains this phenomenon in terms of three hypotheses:

1. The Acquisition-Learning Hypothesis
2. The Natural Order Hypothesis
3. The Monitor Hypothesis

The Acquisition-Learning Hypothesis states that acquisition and learning are different phenomena. We may learn, for example, a great deal about the workings of a car without ever being able to fix one, simply because knowledge about something does not constitute knowledge of something. We may complete a weekend diving course and complete a handful of successful recreational dives, only to forget a few weeks down the road what exactly we're supposed to check before we enter the water, how to swim efficiently with flippers, and how to tell our partner that we're out of air.

I will discuss what I see as the elements involved in this disparity further down the page or later in this blog. For now, you need only think of a time when you forgot to do or apply something you had learned and then were reminded of, only to declare, "Ah!  I knew that!"

The Natural Order Hypothesis states that some items of a language, namely functors, are acquired in a certain order which is consistent across learners, ages, and first languages. In the context of Krashen's theory, it is this hypothesis that explains the discrepancy between learning and acquisition. Items may be learned, or brought into our awareness, even applied under conditions of present awareness, in any order, but will only be truly mastered, or acquired, in an order which is natural to the learner/acquirer. The basic principle of natural order underlies our assumptions, based on millenia of observation, about children's motor development. First they flop, then they the flip, then they roll around, then they sit, then they crawl, then they walk, then they jump, then they run, then they dance, and so on. Something like that. The difference is that in motor development, acquisition of one skill requires or is expedited by acquisition of the previous one, while in language acquisition, no such skill-based "seriation" is apparent.

The Monitor Hypothesis states that learned language can be drawn upon under conditions which allow the learner time to draw upon them, most often conditions which require or remind the learner to draw upon them. Think how often you have stalled or frozen in the middle of a task because you could not instinctively recall the next step, perhaps because the next step did not come easily to mind or because pressure of some sort forced you to rely on second nature.  The Monitor Hypothesis suggests that language items (specifically grammar items) which have not become second nature require deliberate thinking before they will manifest themselves in language production. When we have leisure to employ the Monitor or when we know that correct grammatical form is essential to the success of an utterance, we check our utterances before sharing them.

Taken together, these three hypotheses seem to me to explain the problems that I am currently bent on helping students overcome.