Skehan (1996, 1998) claims that acquisition through comprehensible input alone simply will not work as a recipe for developing a second language to a high level of proficiency. As a result of his reviews of work in cognitive psychology, he proposes that language teaching needs to address three areas of development:

• fluency (ie the effective communicative use, in real time, of known TL forms);
• accuracy (ie the accurate and consistent use of known TL forms);
• complexity (ie the extension of knowledge of TL forms).

Skehan argues that these three areas cannot be developed at the same time through the same type of task: in this, he seems to have a slightly different perspective to both Long and DeKeyser. Therefore, in planning language teaching programmes, we need to think particularly carefully about the design of the learning tasks we offer our learners and the processes they involve: it is the tasks that determine the allocation of learner attention to different areas of language. For example, familiar and structured tasks, such as those that require learners to express personal information (eg where they live, where they work, what they like) in a fairly predictable way (eg in answer to interview questions) will not require huge amounts of attention on content and organization, particularly if learners are allowed to prepare their interview first. Such tasks, according to Skehan, offer opportunities for learners to develop fluency. Contrast that with an oral presentation of a complex issue, such as the rights and wrongs of immigration laws. Skehan hypothesizes that this task will not offer effective opportunities for fluency development because it requires so much attention to ideas and their organization. However, it should encourage learners to extend their target language vocabulary and grammar resources, ie it offers opportunities for complexity development.

Skehan (1998: 114-20) draws up recommendations on the basis on his research review for the kinds of tasks which might promote the three different areas:

The idea here, following both Long and DeKeyser, is to try to ensure that focus on meaning and focus on form are balanced. However Skehan differs from DeKeyser in arguing that the two cannot necessarily be developed at the same time, and from Long in proposing rather more systematic planning for focus on form through task design than Long. Skehan's proposals have become part of the approach known as Task-based Instruction (TBI) that is at the centre of current pedagogic debate in the TESOL (Teaching English to Speakers of Other Languages) field.

What is clear from all three current proposals is that a monolithic view of the second language learning process, such as those exemplified in the three approaches we reviewed at the start of this section (Grammar-translation, Audiolingualism and the Natural Approach) is not supported by SLA research. What is far more problematic is to conclude exactly what kind of approach to second language teaching is the most effective. The answer from SLA seems to be: one that combines opportunities for skill development and concept development, both through explicit and implicit learning.