task based language teaching and hypotheses of language development

around the mid-1980s, a number of hypotheses of language development were proposed. although, there were some critics, from the first day that they were published, they remain popular and influential. they have had a major influence on task – based teaching. nunan (1989: 10) defines “task” as: “a piece of classroom work which involves learners in comprehending, producing or interacting in the target language while their attention is principally focused on meaning rather than form.” krashen is an expert in the field of linguistics, specializing in theories of language acquisition and development. he has formulated four hypotheses as the acquisition-learning hypothesis, the natural order hypothesis, the monitor hypothesis and the input hypothesis. he believes that language development does not require extensive use of rules and boring drills. it requires meaningful interaction in the target language and natural communication. this article tries to explain four theories and their implication for task-based teaching.