A leading theorist in his field of study, Ellis has focused much of his research on task-based language teaching (TBLT). In defining a task, Ellis draws off the definitions provided by others scholars (namely David Nunan and Graham Crookes) by focusing on the successful conveyance of language. Ellis defines the key features of a task as being: A workplan: there is a set of teaching materials and activities which are designated for the learning process. A primary focus on meaning: there is a gap of communication or reason that must be filled through interaction. Students are given the freedom to use the language of their choosing rather than focusing on grammatical form. A real world process of language: the task can take the form of an interaction that is likely or less than likely to happen in the real world. The language process should exhibit real-world communication. One that involves any of the four languages skills (reading, writing, listening or speaking). One that engages cognitive processes: students must utilize cognitive processes through their engagement with the task, such as ordering, analyzing and selecting. A clearly defined communicative outcome: the goal of the activity includes a non-linguistic negotiation for meaning. In his explanation of a task, Ellis careful to illustrate its contrast with an activity, with the former being primarily meaning focused and the latter placing more emphasis on form. This distinction also affects the role of each participant, as a task requires students to act as language users. Alternatively, an activity requires the students to act as language learners. 10 Principles of Instructed Language Learning Through his research, Ellis has worked to provide comprehensive guidance for language teachers. Ellis maintains that despite the theoretical contributions made by Stephen Krashen, Robert DeKeyser, Michael Long and Bill VanPatten to the field of second language acquisition, there is no agreement on form-focused instruction or corrective feedback. In 2004, he compiled a set of 10 principles of instructed language learning that have been considered and challenged by other SLA scholars. These principles include: instruction must enlarge the student's use of formulaic expressions while maintaining a focus on rule-based competence. instruction must ensure meaning-focused input and output. instruction must ensure that students also focus on form. instruction must aim to create a balance between implicit and explicit knowledge of the language. Instruction must account for the student's built-in syllabus (noting the Natural approach to learning