Abstract:
The purpose of this article is to present an overview of second language (L2) task-based language teaching and learning. Prabhu (1987) deserves credit for originating the task-based teaching and learning, based on the concept that effective learning occurs when students are fully engaged in a language task, rather than just learning about language. Ellis (2003b) distinguished between task-supported teaching, in which tasks are a means for activating learners' prior L2 knowledge by developing fluency, and task-based teaching, in which tasks comprise the foundation of the whole curriculum. I am concerned here with the latter of the two. To address the topic, the article is arranged in the following way: (a) the concept of "task," (b) analyzing tasks, (c) sequencing tasks, and (d) implications for future research.

1. The Concept of "Task"
The idea of "task" is not as simple as it might seem. Many definitions and perspectives exist, as shown by the list in Table 1. Each one is discussed in turn.

Task as an Imposed Task, Duty, or Piece of Work
An early definition of task comes from Old North French tasque, which meant a duty, a tax, or a piece of work imposed as a duty. Tasque originated from the Latin tax?re, to evaluate, estimate, or assess (Barnhart 1988, p. 1117). This suggests a task is externally imposed and might be onerous.

Task as an Everyday Piece of Work
Long (1985) defined a task as "… a piece of work undertaken for oneself or for others, freely or for some reward . . . [B]y 'task' is meant the hundred and one things people do in everyday life, at work, at play, and in between" (p. 89).

Task as a Job Responsibility
Task also refers to a job responsibility or duty, that is, a specific part of a particular job that a person is asked to do. For example, the job of an administrative assistant requires the task of scheduling appointments for the supervisor. Jobs can be "task-analyzed" for personnel and training purposes (Smith, 1971). This general view of task again implies that the task is externally imposed on the person from outside.

Task as a General Activity or Exercise for L2 Learners
Many L2 textbooks present activities or exercises for learners to accomplish. Sometimes these activities or exercises are discussed as tasks, without a particular emphasis on outcome.

Task as an Outcome-Oriented L2 Instructional Segment
This perspective is similar to the one above except that it focuses on an outcome that the L2 learner is expected to produce or attain. In this perspective, the task is an outcome-oriented segment of work in a curriculum or lesson plan. This idea came from adult vocational education, then spread to elementary education and other fields, such as L2 learning and teaching (Richards & Rodgers, 2001). Breen (1987) defined a language task as a structured language endeavor which has a specific objective, appropriate content, a particular working procedure, and a range of possible outcomes for those who undertake it. Breen suggested that language tasks can be viewed as a range of work plans, from simple to complex, with the overall purpose of facilitating language learning. In fact, he asserted, "All materials for language teaching . . . can be seen as compendia of tasks" (Breen, 1987, p. 26). In a similar vein, Prabhu stated that a task "is an activity that requires learners to arrive at an outcome from given information through some process of thought, and which allows teachers to control and regulate that process" (1987, p. 17). These definitions underscore the idea that a task is a structured instructional plan that requires learners to move toward an objective or outcome using particular (teacher-given) working procedures or processes. Again, a task is imposed from the outside and does not come from the learner.

Task as a Behavioral Framework for Research
Activity Theory, based on work by Vygotsky (1978) and his colleagues, asks a fundamental question: "What is the individual or group doing in a particular setting?" (Wertsch, 1985, p. 211). Drawing on Activity Theory, Coughlin and Duff (1994, p. 175) distinguished between an L2 task and an L2 activity. In their view, task refers to the "behavioral blueprint provided to students in order to elicit data" for research or assessment. Coughlin and Duff defined activity as "the behavior that is actually produced when an individual (or group) performs a task" (1994, p. 175). This distinction can be crucial if we consider that a task may trigger different activities across individuals and in the same individual on different occasions.

Task as a Behavioral Framework for Classroom Learning
In an instructional setting, following Vygotskian concepts, a task consists of the instructions or directions that the teacher gives students for learning-that is, the behavioral blueprint provided to students in order to elicit learning. In this context, an activity is what students actually do with these instructions, that is, the behavior (regardless of whether it is overtly observable or purely mental) that occurs when students perform a task that has been presented to them.

Summary of the Definitions of Task
There are many viewpoints about and definitions of task. Initially the definitions involved a tax, piece of work, everyday activity, job responsibility, or general activity for learners. In L2 teaching and learning, task is now often viewed as an outcome-oriented instructional segment or as a behavioral framework for research or classroom learning. Most often it still has the connotation of being externally imposed on a person or group, although the connotation of being burdensome or taxing is no longer emphasized. I now turn to ways by which we can analyze tasks for task-based teaching and learning.

2. Analyzing Tasks for Task-Based Teaching and Learning
My analysis of tasks includes the following dimensions: task goals, task types, high versus low stakes, input genre and modality, linguistic complexity, cognitive load and cognitive complexity, interaction and output demands, amount of planning allowed or encouraged, timing, teacher and learner factors, and (as influenced by prior factors) overall task difficulty.

Task Goals
Potential task goals fall into three main groups: focus on meaning, focus on form, and focus on forms (Long, 1997; Salaberry, 2001). These are summarized below and in Table 2. Additional task goals are also described.

Possible Task Goal A: Focus on Meaning
The first potential goal is to focus on meaning. In this type of syllabus, learners receive chunks of ongoing, communicative L2 use, presented in lively lessons with no presentation of structures or rules and no encouragement for learners to discover rules for themselves. This is an analytic syllabus (Wilkins, 1976), in which any understanding of the structure of the language must come from the learner, who might or might not perceive regularities and induce rules (Long & Crookes, 1992, p. 28). Grammar is viewed as developing naturally when the learner is ready for a given structure, so no structures should be discussed. The focus on meaning is sometimes not considered instruction at all, because the teacher can be viewed as simply providing opportunities for L2 exposure (Doughty, 2003).

Possible Task Goal B: Focus on Form
The second potential goal is to focus on form within a communicative, meaningful context by confronting learners with communicative language problems (breakdowns) and causing them to take action to solve the problems. In Long's (1985) view, a focus on form occurs when attention is mostly on meaning but is shifted to form occasionally when a communication breakdown occurs. Many techniques are used to meet this goal, such as "recasts" in which the instructor gives a corrective reformulation of the learner's incorrect production or understanding. With a recast, the learner must discern the difference between the correct contextualized form and the original contextualized form and figure out the underlying relationships and rule. Because the learner is involved with language analysis, this is an analytic syllabus (Wilkins, 1976). In this mode, ". . .[T]hree major components define a focus on form . . .[:] (a) can be generated by the teacher or the learner(s), (b) it is generally incidental (occasional shift of attention) and (c) it is contingent on learners' needs (triggered by perceived problems)" (Salaberry, 2001, p. 105).

However, as Salaberry (2001, adapted from Johnson, 1996) noted, a different type of focus on form occurs when the forms are preselected for tasks, rather than arising from learners' needs (the communication problem or breakdown during a task). This alternative focus on form is found particularly in communication-oriented textbooks, where a focus on meaning comes first, followed by a focus on form. Constraints of textbook tasks cause preselection of forms to occur, thus reducing the possibility of a spontaneous and incidental focus on form, such as that found in Long's model. In the preplanned focus on form model (Salaberry, 2001), the goal is to focus on preselected forms related to meaning-oriented tasks.

Possible Task Goal C: Focus on FormS
The third potential goal is to focus on formS by means of presenting specific, preplanned forms one at a time in the hope that learners will master them before they need to use them to negotiate meaning. The learner must synthesize all of the material himself or herself; hence a focus on formS syllabus is a synthetic syllabus (Wilkins, 1976). Lessons tend to be dull, sometimes arcane, and not oriented toward communication, as though L2 learning could be reduced to memorizing accumulated, small items and mechanistically applying myriad rules.

A Caveat about These Goals
Looking back at the second goal, we see that it combines elements of the first and the third. It provides an emphasis on meaning but with an insertion of form when and where needed by learners. Skehan cautioned that distinctions among these goals are not totally firm because "… the two underlying characteristics of tasks, avoidance of specific structures and engagement of worthwhile meanings, are matters of degree, rather than being categorical" (1998, p. 96).

Potential Additional Task Goals
Additional task goals might include learning how to learn, that is, learning to select and use particularly relevant learning strategies and understanding one's own learning style (Honeyfield, 1993; Nunan, 1989; Oxford, 1990, 1996, 2001b). Learners can learn how to learn while doing a task that involves both language and content, as demonstrated by the Cognitive Academic Language Learning Approach (Chamot & O'Malley, 1994). Goals may also focus on content knowledge, as in learning mathematics or social studies through the L2 (Honeyfield, 1993; Oxford, Lee, Snow, & Scarcella, 1994) or may relate to cultural awareness and sociocultural competence (Nunan 1989; Scarcella & Oxford, 1992). Task goals may differ according to whether there is a single, common task goal (convergence) or multiple task goals (divergence) (Richards & Rodgers, 2001).

Task Types
Many types of L2 tasks exist, particularly in the realm of communicative instruction. Here is a listing of some key task types found in the literature: problem-solving (Nunan, 1989; Pica et al., 1993; Willis, 1996a); decision-making (Foster & Skehan, 1996; Nunan, 1989; Pica et al., 1993); opinion-gap or opinion exchange (Nunan, 1989; Pica et al., 1993); information-gap (Doughty & Pica,1986; Nunan, 1989; Oxford, 1990; Pica et al., 1993); comprehension-based (Ikeda & Takeuchi, 2000; Scarcella & Oxford, 1992; Tierney et al., 1995); sharing personal experiences, attitudes, and feelings (Foster & Skehan, 1996; Oxford, 1990; Willis, 1996a, 1996b); basic cognitive processes, such as comparing or matching (Nunan, 1989; Willis, 1998), listing (Willis, 1998), and ordering/sorting (Willis, 1998); language analysis (Willis 1996a, 1996b, 1998); narrative (Foster & Skehan, 1996); reasoning-gap (Nunan, 1989); question-and-answer (Nunan 1989); structured and semi-structured dialogues (Nunan, 1989); and role-plays and simulations (Crookall & Oxford, 1990; Richards & Rodgers, 2001).

In addition, task types include picture stories (Nunan, 1989); puzzles and games (Nunan, 1989); interviews, discussions, and debates (Nunan, 1989; Oxford, 1990; Richards & Rodgers, 2001); and everyday functions, such as telephone conversations and service encounters (Richards & Rodgers, 2001). Task types also encompass practice with communication/conversation strategies, learning strategies, and text-handling strategies (Cohen, 1998; Honeyfield, 1993; Nunan, 1989; O'Malley & Chamot, 1990; Oxford, 1990). Additional task types can lead to communicative videomaking (Talbott & Oxford, 1989, 1991). For more on various types of tasks, see Bygate et al. (2001) and Yule (1997).

Many task types involve multiple skills and subskills, such as reading a passage for comprehension and then doing something with the information that has been read, such as answering questions, discussing the information, making a decision, solving a problem, and expressing how one feels about a given situation.

Importance of the Task: Low or High Stakes
One aspect of external pressure concerns whether the task is perceived as important, specifically whether it is viewed as a low- or high-stakes requirement. In a low-stakes, relaxed task, there is less stress during the task. In a high-stakes task or set of tasks, such as those found on an English competency examination for graduation or for university entrance, much more anxiety can be expected. Those learners who tend to be anxious anyway may become particularly tense while doing a high-stakes task. Skehan (1996a) discussed the differential effects of low- and high-stakes tasks.

Timing
The amount of time allotted for the task can be a major factor (Honeyfield, 1993; Skehan, 1996a), especially for L2 learners who are at the beginning and low intermediate levels. When a task is "speeded," that is, when only a certain amount of time is given to complete the task, it might become more difficult for some learners. If students are allowed to take all the time they need, i.e., if the task is "unspeeded," this takes off some of the pressure. In-class tasks do generally have a time limit, although, depending on the task type and the goals, some tasks that are unfinished can be done as homework assignments.

Input Genre and Modality
Tasks can be analyzed according to the input genre (newspaper article, diary, recipe, diary, TV show, conversational talk, lecture, and so on) and modality (e.g., written, spoken, graphic/pictorial) (Honeyfield, 1993; Nunan, 1989; Skehan, 1996a). Genre and modality interact. For instance, a newspaper article can be a written text and an accompanying picture, and it can also be read aloud.

Richards and Rodgers (2001) cited a range of input materials for L2 tasks, including books, newspaper, video, TV, and so on. Interest level of the learners in the material is particularly crucial. If materials are perceived as boring or as too easy or too difficult, learners will be unmotivated to do the task (Scarcella & Oxford, 1992). Publishers provide materials of wide interest to most students, although cultural factors such as religion can prevent some materials from being used for L2 tasks in particular locations.

Also, relevance and suitability of task input-and of tasks themselves-also depend on whether the L2 learning occurs in a foreign versus a second language setting. Certain input and tasks would be more available and feasible in a second language environment than a foreign language environment, because in the former there are many more natural resources in the target language and many more native speakers of the language with whom to interact. Yet because of the Internet, the foreign language environment now contains instant L2 input (not just written text, but also multimedia that could help develop multiple skills) that were simply unavailable to learners in times past. In locations where students have easy access to the Internet, teachers can take advantage of new input in simulations and WebQuests. The widespread presence of games and videogames on the Internet creates additional input possibilities. However, in some Asian countries, many learners are already so involved in L1 videogames for entertainment that they might not recognize L2 game-based or videogame-based tasks as a serious endeavor. The context determines the relevance of various types of input.

Linguistic Complexity
An important task factor is linguistic complexity (Dahl, 2004; Foster & Skehan, 1996; Richards & Rodgers, 2001; Skehan, 1996a), such as number of words in a sentence, amount of redundancy, degree of use of dependent clauses and other complexity-creating structures, discourse style, sequence complexity, technicality of vocabulary, concreteness or abstractness, sectioning, and other features. As noted by Dahl (2004), linguistic complexity is not synonymous with "difficulty" but is instead an objective property of a system-a measure of the amount of information needed to describe or reconstruct it. It is the result of historical processes of grammaticalization and involves mature linguistic phenomena (Dahl, 2004). Gibson (1998) indicated that linguistic complexity is a function of the "integration cost" and the "memory cost" associated with keeping track of obligatory syntactic requirements, such as center-embedded dependent structures, placement of large phrases earlier (heaviness effect), and ambiguity effects.

Salaberry (2001) mentioned the following issues involved with task language features: frequency and saliency; and linguistic categories, such as vocabulary, phonology and phonetics, morphosyntax, discourse, pragmatics/speech acts, and sociolinguistics. All of these contribute in various ways to the degree of linguistic complexity.

Linguistic complexity is not the same as "difficulty." The person's familiarity with the material, the topic, or the language properties mitigates some of the difficulty even when the linguistic material is complex. The difficulty is also affected by the number of language skills (reading, writing, speaking, and listening) and subskills required to do the task
.
Cognitive Load and Cognitive Complexity
Cognitive load is another feature of the task. The concept of cognitive load relates to Sweller's (1988, 1999) assumption that people's capacity to process information is limited. The more that a learner tries to hold in his or her head at a given moment, the harder the learning is and the more likely there will be a cognitive overload. Another assumption is that some tasks have a higher cognitive load. For instance, the task of integrating information from multiple sources might have a higher cognitive load than the task of following an example. Cognitive load can be increased by competing stimuli in the input or during the task, distracting the learner.

Cognitive complexity is yet another characteristic, but it relates not just to the task but also to the person. Analysis of cognitive complexity has been defined as "an aspect of a person's cognitive functioning which at one end is defined by the use of many constructs with many relationships to one another (complexity) and at the other end by the use of few constructs with limited relationships to one another (simplicity)" (Pervin, 1984, p. 507). Therefore, cognitive complexity involves a person component (unobservable cognition and observable behavior) and a task structure component. If a computer is involved, there is also an interactive system component (Rauterberg, 1992).

The task-required cognitive processing operations can be complex (Foster & Skehan, 1996; Ikeda & Takeuchi, 2000; Richards & Rodgers, 2001; Skehan, 1996a), but not every cognitively complex task is viewed as difficult. Whether or not a particular student actually perceives a given, cognitively complex task to be difficult and challenging depends considerably the student's familiarity with the kind of cognitive operations required.

Interaction and Output Demands
Presence or absence of a demand for output is a task factor. Swain (1985) and Scarcella and Oxford (1992) emphasized the importance of students' providing comprehensible output in task situations, often through interaction with others. Task interaction may be one-way, as in one person talking and the other listening or writing notes. It may be two-way (Long, 1985; Richards & Rodgers, 2001), as in two individuals engaged in an information-gap task (Doughty & Pica, 1986; Nunan, 1989) or sharing personal experiences (Foster & Skehan, 1996). It may be multi-way, as in a group discussion, role-play, or simulation (Crookall & Oxford, 1990). Among many examinations of which types of tasks promote L2 learning (see, e.g., Plough & Gass, 1993; Robinson, 1995; Yule et al. 1992), a review by Pica et al. (1993) reported that negotiation of meaning is most likely to occur when learners are involved in an interaction with the following four features:

Thus, qualitative differences in the nature of the negotiation of meaning resulting from different tasks and different types of interaction, as Nunan (2004) also pointed out.

However, interaction and output might not be essential, depending on the task purpose. For learning the use of relative clauses, Tanaka (1996, in Ellis, 2003a) found that practicing with input proved to be more efficient than practicing with output (using relative clauses in traditional production-practice tasks). Input practice tasks helped students understand relative clauses better, and their ultimate production ability was just as strong with input practice tasks as with traditional production-practice tasks.

When production practice is the goal of the task, complexity of the output becomes a task factor. Output complexity relates to the complexity of language the learner uses and the cognitive sophistication of the output, both of which depend on the learner's willingness to take risks in restructuring forms and concepts (Foster & Skehan, 1996; Skehan, 1998b).

Allowable Amount of Planning
The amount of planning (a metacognitive learning strategy; see Oxford, 1990) allowed or encouraged is a factor in how well the learner accomplishes the task. Foster and Skehan (1996) examined the influence of task type and degree of planning on three different aspects of L2 performance: fluency, accuracy, and complexity. The study employed three types of tasks (personal information exchange, narrative, and decision-making) under three planning conditions (unplanned, planned but without detail, and planned with detail). Results indicated that planning had clear effects on both fluency and complexity of participants' output. However, planning was not the key to accuracy. In fact, less detailed planners were more accurate than non-planners and those who planned in detail. Interactions emerged between task type and planning conditions. Effects of planning were greater with narrative and decision-making tasks than with personal information exchange tasks. In their discussion, Foster and Skehan noted that a trade-off existed between the goals of performance complexity and performance accuracy. They explained that individuals have a limited capacity for attention, as noted earlier, so when a task is more cognitively demanding, attention is diverted from formal linguistic features-the basis of accuracy-to dealing with these cognitive requirements.

Sometimes when learners are allowed an opportunity to plan, this makes the task seem easier, but at other times the allowance of planning sends a signal that this is a difficult task, which makes certain learners anxious. The way the planning is introduced and implemented influences the value of planning.

Timing
The amount of time allotted for the task can be a major factor (Honeyfield 1993; Skehan 1996a), especially for L2 learners who are at the beginning and low intermediate levels. When a task is "speeded," that is, when only a certain amount of time is given to complete the task, it might become more difficult for some learners. If students are allowed to take all the time they need, i.e., if the task is "unspeeded," this takes off some of the pressure. In-class tasks do generally have a time limit, although, depending on the task type and the goals, some tasks that are unfinished can be done as homework assignments.

Teacher Roles and Characteristics
Teachers can take many different roles in regard to L2 tasks (Honeyfield, 1993; Nunan, 1989; Oxford, 1990; Scarcella & Oxford, 1992; Willis, 1996a, 1996b, 1998). Richards and Rodgers (2001) and Scarcella and Oxford (1992) mentioned the following task roles for teachers: selector/sequencer of tasks, preparer of learners for task, pre-task consciousness raiser about form, guide, nurturer, strategy-instructor, and provider of assistance. Cultural and linguistic backgrounds and teaching styles influence the roles teachers feel comfortable taking (Oxford, 2002; Oxford, Massey, & Anand, 2003; Scarcella & Oxford, 1992). The amount and kind of help provided by the teacher was singled out as a task-related teacher factor by Honeyfield (1993) and Scarcella and Oxford (1992).

Learner Roles and Characteristics
Richards and Rodgers (2001) and Scarcella and Oxford (1992) identified possible task roles for learners, such as group participant, monitor, risk-taker/innovator, strategy-user, goal-setter, self-evaluator, and more. Others (Honeyfield, 1993; Nunan, 1989; Oxford, 1990) have also discussed learners' task roles. A particularly important learner role in a task situation is that of task-analyzer. The learner must analyze task requirements and find suitable strategies to match them.

The learner can take control of the task-that is, be responsible for his or her performance on the task-by considering the task requirements and employing learning strategies to accomplish the task more efficiently and more effectively (Cohen 1998; O'Malley & Chamot, 1990; Oxford 1990). On the part of the learner, this involves a serious commitment, motivation, confidence, clarity of purpose, and willingness to take risks (Dörnyei 2001; Dörnyei & Schmidt, 2001; Honeyfield, 1993; Oxford, 1996; Skehan, 1998b; Willis, 1996a, 1996b, 1998), but these may be dampened by language anxiety (Arnold, 1998; Oxford, 1998; Young, 1998).

Learning styles are likely to affect choice of strategies for accomplishing tasks (see Oxford, 2001). Learning styles also make a difference in which tasks are perceived as difficult by individual learners. For example, face-to-face communication tasks might be viewed as easier for a person with an extroverted learning style than an introverted learning style. Learners whose learning style is highly analytic, concrete-sequential, and/or closure-oriented might perceive greater ease in accuracy- and form-focused tasks than fluency tasks.

Overall Task Difficulty
Honeyfield (1993) specified the following influences on general task difficulty: procedures to derive output from input; input text; output required, such as language items (vocabulary, structures, etc.), skills, or subskills; topic knowledge; text-handling or conversation strategies; amount and type of help given; roles of teachers and learners; time allowed; and learner characteristics, such as motivation, confidence, and learning styles. For Skehan (1996a), factors related to task difficulty include: code (language) complexity, cognitive complexity (cognitive processing, cognitive familiarity), and communicative stress (time, modality, scale, stakes, and control).

Summary of Analyzing Tasks for Task-Based Teaching and Learning
This section has discussed factors that are often analyzed with regard to L2 tasks. Some of the major factors are complexity (linguistic and cognitive); overall difficulty, which is not the same as complexity; and roles of learners and teachers. How we can sequence tasks and parts of tasks is the topic of the next section.

3. Sequencing Tasks for Task-Based Teaching and Learning
As noted by Richards and Rodgers (2001) and Willis (1996a, 1996b, 1998), a task has a natural series of stages, such as preparation for the task (pre-task), the task itself, and follow-up (post-task). Many L2 learner textbooks now follow this practice. In addition, tasks are often placed into a sequence as part of a unit of work or study. Sequencing is a major issue in a task-based syllabus. Swales (1990), tasks are "…sequenceable goal-directed activities…relatable to the acquisition of pre-genre and genre skills appropriate to a foreseen or emerging . . . situation" (p. 76, in Salaberry, 2001, p. 102). Skehan (1998b) noted that tasks have discernable implementation phases, for which there should be clear criteria for outcomes assessment.

The traditional presentation-practice-production (PPP) teaching/learning cycle was at one time virtually the only acceptable L2 task sequence. In the PPP cycle, grammar presentation came first, followed by controlled and less controlled practice and then by actual production. However, Willis' (1996a, 1996b, 1998) task-based model offers a task cycle that opposes the PPP sequence. In this model, which effectively combines meaning and form, the communicative task comes before the focus on form (language analysis and practice). Another special feature is that students not only do the task but also report on it. Willis' framework consists of the following:

Nunan (2004) argued in favor of units based on topics or themes in which Halliday's (1985) three groups of macrofunctions are divided into microfunctions, each linked with certain grammatical structures. Nunan's task-based syllabus contains six stages per unit:

It is interesting that Nunan, unlike Ellis (2003) and Long (1985, 1991, 1997), waited until the very end of the process to include the communicative task. In Nunan's model, the task is a culmination of all other work. In this sense, as noted by Feeney (2006), this is not too far from the PPP format, except that Nunan's controlled practice occurs within more of a communicative context than is usual with the PPP arrangement. Nunan's focus on form occurs before both freer practice and the task, whereas Willis's (1996b) model employs a focus on form after the task.

Long's (1985, 1991, 1997, 2005) task-based language teaching model presents a focus on form, which involves meaning, structure, and the context of communication. The model follows the following sequence of task development, implementation, and assessment/evaluation:

In Long's model, tasks are selected based on careful analysis of real-world communication needs. Such tasks are particularly important-even catalytic-for L2 learning because they can generate useful forms of communication breakdown (Long, 1985). The teacher offers some kind of assistance to help the learner focus on form at the point when it is most needed for communication. This is the moment when meaning meets form. While not explaining the learner's error, the teacher provides indirect assistance so the learner can solve his or her own communication problem and can proceed to negotiate meaning still further. Long (1997) presented the following typical instructional sequence for a "false beginner" class of young adult prospective tourists.

In this model, the exact sequence of any given task or set of tasks would depend on the learners' needs, which shape the goals of instruction.

Ellis (2003b) distinguished between (a) unfocused tasks (e.g., ordinary listening tasks or interactions) and (b) focused tasks, which are used to elicit a particular linguistic feature or to center on language as task content. He cited three principal designs for focused tasks: comprehension tasks, consciousness-raising tasks, and structure-based production tasks. Elsewhere (Ellis, 2003a) presented a sequence of tasks for helping learners become more grammatical, rather than for attaining the elusive goal of mastery. The sequence includes:

Johnson (1996), Skehan (1998b), and Willis (1996b) discussed sequencing of tasks according to methodological task features, such as extent of communication (negotiation of meaning), task difficulty, and amount of planning allowed. Others have discussed how to sequence tasks to reflect the developmental sequence of language acquisition. Skehan (199b) suggested targeting a range of structures rather than a single one and using the criterion of usefulness rather than necessity as a sequencing criterion.

Salaberry (2001) argued that a successful task sequence leads learners to: (a) communicate with limited resources, (b) become aware of apparent limitations in their knowledge about linguistic structures that are necessary to convey the message appropriately and accurately, and finally, (c) look for alternatives to overcome such limitations. Building on the work of McCarthy (1998), Salaberry offered a pedagogical sequence of four stages, which for the learner would be involvement, inquiry, induction, and incorporation. For the teacher the corresponding four-step sequence is introduction of the topic, illustration, implementation, and integration. See Table 3. This sequence is very detailed and includes multiple tasks at each stage.

Table 3 Four stages of teaching/learning showing sequence of tasks

Teacher		Learner	Salaberry's example
1. Introduction of topic		1. Involvement (motivation to participate in the task)	Teacher illustrates particular features; students rate various movie reviews written by movie critics on a scale from the most positive to the most negative.
2. Illustration		2. Inquiry (communicative analysis of language in communicative context; mostly initiated by learners, not the teacher)	Teacher reads a movie narrative and asks students to identify events in the plot (in infinitive form); students separate main events from minor events; students reconstruct story in writing in present tense.
3. Implementation		3. Induction (development of hypotheses about structure and functions of the language)	Students do a listening comprehension task: place pictures of main movie events in correct order. Then they listen to the tape again to write down as many plot events in past tense as possible while tape is played to reconstruct whole plot, including minor events (modified dictogloss). Students have not yet had a formal explanation of past tense endings, but teacher can informally give past tenses of various verb types from student narratives in #2. During the [essential] debriefing stage students may be given the actual script that was read to them so that they can compare it to their transcription; this is crucial for allowing students to verify, modify, or reject their hypotheses (from induction). Learner controls the learning process.
4. Integration		4. Incorporation (assimilation of knowledge about new L2 features in a way productive to the overall L2 system)	Students produce their own movie scripts (incorporation). For instance, they can be asked to write a dialogue for a series of (scrambled) pictures that recount a possible eye-witness account of an event parallel to the movie plot (#3). They act out the scene (concrete outcome).

Source: Summarized from Salaberry (2001, pp. 108-110).

It is evident that no consensus yet exists about the best way to sequence tasks or to sequence elements within tasks. This is one of the key areas of research needed in the field. The next section offers a set of implications for research.

4. Implications for Future Research
Researchers have made significant strides in this field. However, it will be important to keep focusing on what is meant by "task-based L2 teaching and learning." The term can evoke many different images, depending on which theorists and models are involved and on various and locations in which such teaching occurs. We have seen many variations and possibilities above. The definitional and conceptual question,

From these questions and from the whole article it is clear that task-based teaching and learning as a field is an exciting field that is experiencing much ferment at this time. Task-based teaching and learning potentially offer great riches if explored by teachers in their dual roles as instructor and action researcher. Professional researchers can provide additional answers to the questions raised here. The answers will enhance the teaching and learning of languages around the world. The ultimate beneficiaries will be the students whose needs will be more fully met if the questions are clearly raised, explored, and answered.

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