The task-based approach to language teaching has evolved in response to a better understanding of the way languages are learnt. Traditionally, language learning has been regarded as a process of mastering a succession of steps, each one building on the one before. Teachers present the target language in ready-to-assimilate pieces, starting with the easy parts and gradually moving towards the harder parts. Learners must master each part and incorporate it into their knowledge of the target language. The PPP model of language teaching (‘presentation, practice, performance’) is based on the assumption that a language is best presented to learners as a syllabus of structures, and that through controlled practice a fluent and accurate performance of the ‘structure of the day’ can be achieved. Errors are evidence of poor learning, requiring more PPP treatment.