Why teach grammar?
Regardless of which approach or what methods are used, most foreign language students will find themselves severely handicapped by an institutional structure that works counter to their best interests. Most teachers realize that their students will not become truly proficient solely because of their teaching prowess. Rather, nearly all students who reach a high level of proficiency will do so as the result of personal initiative that includes a committment to invest far more time than is currently expected in the typical high school or university setting.
Imagine if a student were to attend a 5-minute class, taught by a non-native speaker, once a week, for the period of one month. What level of proficiency would you expect this student to attain? Contrast the above example with the student who travels to the mother country, enters an intensive foreign language program, lives with a host family, makes friends who speak only the target language, and actively seeks out experiences to become immersed in both the language and the culture. Would you expect a higher level of achievement from this student?
Clearly, "quantity counts."
Having established the importance of quantity, we must now ask the question, "What quantity of language instruction is required to achieve the desired goal?" and here's where the issue gets thorny because, while quantity is essential, "quality" is also important. But what represents "quality instruction" is not really all that mysterious. If the instruction is authentic, comprehensible, and engaging, then it is quality instruction. We can go deeper and say that there are differing levels of quality, and that is also true, but all of this nail-biting and hand-wringing over discovering or mastering the "best" method is to grab the wrong end of the stick. The bigger problem is one of quantity, not quality, and that's why even when the student receives quality instruction, his achievement often falls short of expectations.
Something has to give. Either the expectations have to be lowered, or the quantity of instruction must be increased. Unfortunately, the average foreign language teacher has no control over either of these factors, and often finds herself in the untenable position of having to meet standards which simply do not correlate with the quantity of instruction that the student receives. It is no wonder then, that the teacher is left searching for the “silver bullet” that will help her solve this conundrum.
Taking the difficult position of the language teacher and stretching it to an absurdity, imagine that you have 10 seconds to teach someone Spanish. If it were me, I would tell the student, “Spanish is pronounced just like it is spelled, and there are a lot of words that look like their English counterparts.” This would serve the student far better than using the 10 seconds to model authentic language in a comprehensible fashion. If I had 20 seconds, I might add, “The vowels in Spanish are always pronounced the same way, and they are always short, crisp and pure.” The point is that if the quantity of instruction is severely constrained, the teacher must adopt strategies that get the most “bang for the buck.”
Enter, grammar teaching.
The value (or lack thereof) of teaching grammar is a frequent topic among language professionals. While its value with regards to its effect on deep acquisition remains debatable, most teachers would probably agree that learning rudimentary and even advanced grammar empowers the student to “work with” the language and “perform” in the language, even if only (as suggested by its detractors) temporarily and on a superficial level. It gives the student essential tools that allow him to self-monitor his production, and serves as a springboard for production that precedes deep acquisition. If you believe that there is a correlation between production and acquisition, and you believe that grammar instruction facilitates production, it then becomes very difficult to argue that teaching grammar does not also facilitate acquisition.
But more importantly, as long as the prevailing paradigm of foreign language instruction is restricted to a few hours a week, it is unreasonable to expect high levels of achievement. There will be exceptions of course but, by and large, students will continue to achieve only low levels of proficiency and, for many, their experience in the foreign language classroom will be one of frustration at best, failure at worst. The goal of learning a second language will continue to be one that is viewed as largely unattainable. These negative effects are primarily the result not of poor teaching or a poor curriculum, but rather of an institutional unwillingness to allocate sufficient resources to the task. In this case, the specific resource is time itself. But these negative effects can be at least partially mitigated by placing value on the mastery of grammar, because explicit grammar instruction offers a real opportunity for the student to succeed within a framework that makes the higher goal, true mastery of the language, unattainable.
And that, given the current state of affairs, is the most important reason for teaching grammar.