A task-based lesson uses a task as its main component. In designing this kind of lesson, the stages or phases of the lesson — pre-task phase, during-task phase, and post-task phase — must be carefully considered. The pre-task phase is concerned with the activities the teachers and learners can undertake before they start with the task; the second, on the task itself; and the third, on the procedures by which the task performance can be followed up. Of these three, only the second is obligatory. But while it may be so, the other phases — the pre- and post-tasks — may be crucial in ensuring that the performance of the task is effective for language development.
The pre-task phase may be used to motivate the students to actively participate in the task and/or to make them understand the importance of participating in the task, hence, raising the likelihood of them actively participating in the during-task phase. A teacher can do the pre-task phase by doing any one of these four ways: (1) by supporting learners in performing a task similar to the task they are to perform in the during-task phase of the lesson; (2) by asking students to observe a model perform the task; (3) by engaging learners in non-task activities that will prepare them for the task; and (4) by conducting a strategic planning of the main task together with the students.
For the during-task phase, the teacher has two options: those relating to how the task is to be undertaken (task-performance options) and those that involve the teacher and students in on-line decision-making about how to perform the task (process options).
For the task-performance options, the teacher may have to decide whether or not he/she should set a time limit, whether or not he/she should allow students access to the input data, and whether or not he/she should incorporate some surprise element into the task.
Giving students unlimited time seems to encourage accuracy; whereas, setting a time limit seems to encourage fluency. Allowing input data often depends on the design of the task. And finally, incorporating surprise element into a task does not seem to have any effect on the fluency, complexity or accuracy of the learners’ language.
The post-task phase allows for three options: having the students do a repeat performance, reflection on the task, or focus on forms. Requiring students to repeat a task allows them to improve their performance, in terms of fluency, complexity, and proposition use, among others. Asking the students to reflect on the task — how they did it and what they decided or discovered — via oral or written report may contribute to the development of the students’ planning, monitoring, and evaluating skills. Finally, focusing on forms at the post-task phase may counter the likelihood of students developing fluency at the expense of accuracy.