- The teachers disagree -
For evidence that the explicit teaching of language doesn't enhance acquisition: Please see: Krashen, S. 2003. Explorations in Language Acquisition and Use (Heinemann).
We have enough evidence to support the hypothesis that there is a natural order, but we don't know the order for every bit of language. Nor do we need to know it. If acquirers get lots and lots of comprehensible input, all the grammar they are ready to acquire is automatically there in the input. We don't have to teach along the natural order or along any other grammatical syllabus.
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Any theory of explicit grammar teaching's value in language acquisition depends on there being an adequate theory of grammar. The basic simple fact is that linguistics as a science has not yet developed a totally adequate theory of English grammar. English linguistics as a science cannot adequately account for grammar as it has competing theories of grammar none of which account for the language knowledge we actually use.
This can be argued as normal in science. For example in physics there is black matter, black energy and negative black energy all of which cannot be accounted for by any theory of physics. Theories of hadrons indicate hadrons which have not yet been discovered.
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The English grammar taught in English textbooks is not English grammar. It is Latin Grammar imposed by grammarians on English. That is a historical fact. We are teaching grammatical concepts not derived from the examination of English but transfered from the study of other languages. They don't fit except as rules of thumb. They have no scientific basis, but just approximate English. It only works where there is no semantic ambiguity.
Grammar works where one has a strictly limited narrow and well defined semantic field defined in strict narrow dictionary lexicon where one to one word to word translation is the standard. Grammar is 100% about entrance into the elite discourse community. So it is important for social reasons
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Teaching English grammar is teaching English
Quirk, Greenbaum, Leech, Svartik: A Comprehensive Grammar of The English
Language, Longman 1985
Biber, Johansson, Leech, Conrad, Finega: Longman Grammar of Spoken and
Written English, Longman, 1999
Carter and McCarthy: Cambridge Grammar of English, CUP:2006
Sinclair (editor-in-chief): Collins Cobuild English Grammar, Collins, 1990.
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Grammar is an issue because it is finite and testable, whereas language is ambiguous, context based and difficult if not impossible to measure.
Many modern testing experts have agreed that there are few or no reliable tests of writing skill. English language is a skill and an art form. People who use English fluently do not fit into those testing boxes.
One of the most significant parts of English grammar is word formation and functions. Like is a noun, a verb, an adjective, a preposition and difficult to explain how and why. The hard working English verbs get, be, have, and do do more work than other verb forms.
Good luck
