This is hard to type up but it’s worth doing so people will understand why a natural order of acquisition is important to establish (p.s. this doesn’t tell WHY it’s so hard to establish)
From Second Language Teaching and Learning by David Nunan (a basic text in the field), p.43
“THE MORPHEME ORDER STUDIES
One of the most influential scholars to have written on the relationship between instruction and acquistion is Krashen (1981, 1982). Krashen developed his hypotheses out of a series of investigations carried out during the 1970s. Known as the “morpheme order studies,” these investigations set out to determine whether there is a “natural sequence” in the aqcquisition of second language grammar. The researchers found that, in fact, learners from very different first language backgrounds (for example, Spanish and Chinese) appeared to acquire a set of grammatical items (or morphemes) in English in virtually the same order (Dulay and Burt 1973, 1974). The first studeies were carried out with children. Later investigations involving adults came up with very similar acquisition orders (Bailey et al. 1974). From these investigations, researchers concluded that it was the nature of the language being learned, and not, as had previously been thought, a contrast between the first and second languages, that determined the order of acquisition. The next step was to see whether these orders could be “overturned” by instruction. The results were disappointing (at least for those who wanted to make strong claims about the relationship between instruction and acquisition). Not one study showed that the so-called natural order could be changed through instruction. It was also found that knowledge of grammatical rules was no guarantee of being able to use those rules for communication. Learners who were able to identify instances of rule violation, and who could even state the rule, frequently violated the rules when using language for communication.”
I hope everyone understands the salient points of this:
#1 there is a natural order although it hasn’t been establish for languages other than English and perhaps Spanish
#2 this order cannot be changed through instruction
#3 knowledge of the rule did not have the desired effect of allowing the knower of the rule to use it in communication
The implications of this for classroom instruction are enormous: it says that all of that instruction is for naught and we really should keep up the CI if we expect learners to be able to communicate with any sort of grammatical accuracy.
It is up to the doubters to overturn the results of the studies.