1.1 Introduction
Language teachers are faced with making complex and consequential decisions at various phases in teaching, from lesson planning to classroom teaching, homework grading, assessments, and so on. For example, should a particular grammatical feature be introduced? If so, when, and how? How could the texts be adjusted to the studentsā level of knowledge? Should the original text be simplified or left intact and supplemented with a glossary and a grammatical explanation? Should the contextual or background information be provided rather than helping with difficult language structure and vocabulary? How could students be incentivized to talk more or produce more spoken language? Does a mixed-level class or grouping have an advantage over a homogeneous one? At what point should accuracy be prioritized over fluency? Which or what kinds of errors should be taken seriously and corrected, and how?
A language teacher displays professionalism through their awareness, knowledge, and rationale for each choice described above. It is imperative that the field of language education and the teacher preparation program equip the teacher with conceptual frameworks and guidelines for discovering and navigating a variety of possibilities of language pedagogies. The history of foreign language teaching has seen different schools and approaches become prominent and dominant and then recede, from grammar translation to audio-lingual methods to the current communicative approaches. With the rise of second language acquisition (SLA) as a field of inquiry, more systematic and rigorous research has been conducted to evaluate the effectiveness of specific approaches to and techniques for foreign language teaching.
This chapter concerns what SLA, with its theoretical frameworks and empirical evidence, could offer to language pedagogy in general and the specifics of instruction in the classroom and beyond. Let us start by clarifying what is meant by āsecond languageā or L2. Second language comprises āany languageā which is learned āsometime later than the acquisition of the first languageā (Mitchell et al., 2013: p. 1). First language or languages (L1) are typically learned āfrom the womb up to about four years of age,ā and second language (L2) refers to any language learned after the L1, hence often called additional languages (Ortega, 2013: p. 5).1 Given that L2 is a construct for distinction with L1, it should not be surprising that, in SLA literature, L2 refers to both second language and foreign language instead of making the distinction customary in discussion of language pedagogy. Different contexts of learning denoted by SL and FL, namely, whether the linguistic environment outside of the classroom is in the target language or not, are not always central in SLA research.
1.2 First and second language acquisition
SLA has drawn on the insights and methodology of Child First Language Acquisition research, as well as being broadly influenced by linguistics and psychology. In particular, early conceptualizations of second language acquisition were inspired by L1 acquisition research, such as Roger Brownās findings of the order of acquisition of English morphemes by L1 children. L2 English morpheme studies followed the suit to analyze cross-sectional data of different language groups and learners of different ages. Surprisingly, a similar, though not identical, order of morpheme acquisition was observed across the learner groups, regardless of L1 background, age, and learning environment. For one, ābeā is used first as a copula (āit is coldā) and then as an auxiliary in the progressive construction (āit is rainingā). For another, irregular past (āwentā) is marked before regular past (āplayedā) (Krashen, 1982: p. 13). These observations constituted a watershed moment in the development of SLA research.
1.2.1 Age
The introduction of L2 morpheme studies revealed an unforeseen similarity between L1 and L2 acquisition. However, differences between L1 and L2 acquisition processes, including the age of the learner, call for serious attention. L2 learning occurs later in life, whereas L1 learning begins with, or even before, birth. The conventional wisdom is that the earlier L2 learning takes place, the better. We should ask, if so, why the younger learner has the advantage? Is it a biological clock, as is commonly believed? Is an older learnerās brain not as plastic as a younger learnerās? Or is the issue of age a social one rather than a biological one? That is, is it because the older learner likely has lower access to target language speakers or higher anxiety about speaking and communicating in L2? Or is it not at all an issue of age? Could it instead be that L1 is so entrenched in an older learnerās linguistic system that L2 development is inevitably ātaintedā by L1?
Age as a biological property is a hotly debated factor in SLA in relation to the nature and level of linguistic knowledge attained and the mechanism of learning. Earlier research looking into the relationship between increasing age and knowledge of L2 found that younger learners have an advantage in phonology and morphology, but not necessarily in all levels of language such as syntax and vocabulary. More recent studies attempting to identify locations and patterns of brain activities in language processing have not yielded a definitive answer about whether the brain functions fundamentally differently for language learning in older age (Ortega, 2013).
Other environmental issues are critically associated with age. For example, children learning L1 are exposed to millions of utterances directed to them until they master the language, whereas L2 learners starting at later ages are not. It is not only a matter of quantity of exposure or amount of language input, but also of quality of exposure. It is crucial for input to be useful. That is, it is not enough to be surrounded with a vast amount of input. Novel language forms must be noticed and comprehended. L1 learning children receive input that is tailored to their needs, whereas older L2 learners are not accommodated to the same extent. Motivation for making efforts to make sense of new language also differs between L1 learning children and older L2 learners, as the necessity of learning L2 varies greatly depending on individual life circumstances for the latter group.
Age is also entangled with whether the language being learned is L1 or L2. Unlike L1 learning children, older L2 learners have a well-established knowledge of a language (i.e., their L1). Should knowledge of a language not help acquiring another language? Would it interfere with forming a correct representation of a different language? In the view of the earlier structuralist/behaviorist approach which characterized language learning as the acquisition of new habits, L1 knowledge is a set of old habits that interfere with forming new L2 habits. Later approaches have shown that L1 plays more a complex role, facilitative as well as obstructive, mediating L2 learning in different ways depending on specific linguistic features and perceived difference or similarity. While views about the exact role of L1 vary, L2 development clearly does not take place on blank slate, but in the interstice with L1. This will be discussed further in Section 1.3.2.
1.2.2 Commonality of first and second language acquisition
While admitting L2 acquisition is distinct from L1 acquisition in various ways, the commonality between L1 and L2 acquisition has received attention with respect to developmental trajectories. Based on the L2 English morpheme studies described above, Krashen (1981) proposed an influential model of second language acquisition which comprises five hypotheses: (i) the acquisitionālearning distinction, (ii) the natural order, (iii) the monitor, (iv) the input, and (v) the affective filter. Acquisition, which is a subconscious process of language development through using language for communication, is distinguished from learning, which is gaining a conscious knowledge of a language. Acquisition is supposed to result in internal grammar represented in the brain which is unconsciously and automatically tapped into for real-time language use. On the other hand, explicit knowledge from conscious learning is not accessed for processing and generating utterances in real time. For example, learners often produce inaccurate forms such as ĆŖĀ·Āø ƬĖĀĆā¢āĆ«Ā„Ā¼ Ƭā¹Ā«Ć¬Å ĀµĆ«ā¹ĖĆ«ā¹Ā¤, despite having ālearnedā the case marking and grammatical structure of emotive verbs (i.e., -ĆŖĀ°ā¬ ƬĀ¢ā¹Ć«ā¹Ā¤/-Ć«Ā„Ā¼ ƬĀ¢ā¹Ć¬ā¢āĆā¢ĖĆ«ā¹Ā¤, -ĆŖĀ°ā¬ Ƭā¹Ā«Ć«ā¹Ā¤/-Ć«Ā„Ā¼ Ƭā¹Ā«Ć¬āĀ“Ćā¢ĖĆ«ā¹Ā¤). The second hypothesis is that acquisition of grammatical structures proceeds in a predictable order. In addition to L2 English morpheme studies demonstrating striking similarities among different groups of learners as mentioned above, developmental ...