Krashen, S. (1982). Principles and practice in second language acquisition. Oxford:
The journal article, Principles and Practices in Second Language Acquisition, investigates the acquisition of a second language and consists of five main hypothesis. The five main hypothesis are the Acquisition-Learning hypothesis; the Monitor hypothesis; the Input hypothesis; the Natural Order hypothesis; and the Affective Filter hypothesis. The first hypothesis, the Acquisition-Learning hypothesis focuses on two independent systems of second language performance. The first is the ‘acquired system’ and relates to the process when a child acquires their first language. The second system is the ‘learned system’ and refers to the product of formal instruction. Both independent systems are relevant. However, Krashen expressed that ‘learning’ is less important than ‘acquisition’. The next hypothesis, the Monitor, explains the connection between the acquisition and learning and discusses the roles that the first languages play in the acquisition in a second language. Teachers are recommended to support students in using monitors and is used primarily in writing and planned speeches and not in ordinary conversations. The third hypothesis, the Input hypothesis discusses how learners acquire a second language. The research illustrated that the students make connections when they receive information that is just beyond their current linguistic competence. A student can understand the second language input, yet it would be difficult and challenging for them to produce it themselves. The fourth hypothesis is the Natural Order, and the research findings suggest that there are certain grammatical structures occurring early in the language acquisition and others acquired later. The Affective Filter hypothesis is the final hypothesis and focuses on variables related to motivation, self-confidence, a healthy self-image, and levels of anxiety. An individual who displays positive traits with motivation, levels of self-confidence, positive self-image, and low levels of anxiety are advantageous for learning a second language. In contrast, an individual with a negative outlook and displays low self-confidence, negative self-image, and high levels of anxiety create mental blocks and as a result language acquisition is impeded.