SLA and It's Related Disciplines

The study of how second languages are learned is part of the broader study of language and language behavior. It is not more central or peripheral than any other part of linguistics study, which in turn has as its larger goal the study of the nature of the human mind. In fact the mayor goal of second language acquisition research is the determination of linguistic on the formation of second language grammar. Some related discipline of second language acquisition are:
a. Language Pedagogy
Most graduate programs whose goal is to train students in language teaching now have required course work in second language acquisition. People have come to realize that if one is to develop language methodologies, there has to be a firm basis for those methodologies in language learning. It would be counterproductive to base language teaching methodologies on something other than an understanding of how language learning does and does not take place. In other words, pedagogical decision making must reflect what is known about the process of learning, which the domain of second language acquisition. Second, rationale related to language pedagogy has to do with the expectations that teachers have of their students.
b. Cross Culture Communication and Language Use
We have noted some expectation that teachers have about students. Similarly, in interactions with speakers of another language/culture, we have certain expectations and we often produce stereotyped reactions. For example, we may find ourselves making judgments about other people based on their language. It turns out that many stereotypes of people from other cultures (e.g. rudeness, unassertiveness) are based on patterns of nonnative speech. These judgments in many instances are not justified, because many of the speech patterns that nonnative speakers use reflect their nonnativeness rather than characteristics of their personality.
c. Language Policy and Language Planning
Many issues of language policy are dependent on a knowledge of how second languages are learned. For example, issues surrounding bilingualism, such as the English Only Movement in the United States, or the many different types of bilingual education (including immersion program) can only be debated if one is properly informed about the realities and constraints of learning a second language. National language programs often involve decision making that is dependent on a). Information about second language learning, b) the kinds of instruction that can be brought to bear on issues of acquisition, and c) the realities and expectations one can have of such programs. All too often, these issues are debated without a clear understanding of the object of debate, that is, the nature of how second languages are learned.

In sum, second language acquisition is a complex field whose focus the attempt to understand the processes underlying the learning a second language. It is important to reemphasize that the study of second language acquisition is separate from the study of language pedagogy, although this does not imply that there are not implication that can be drawn from second language acquisition to the related discipline of language teaching.