Krashen outlines 5 hypotheses about second language acquisition: 1) Acquisition/Learning distinguishes subconscious acquisition from conscious learning. 2) The Natural Order Hypothesis states teachers should not follow ordered grammar patterns. 3) The Monitor Hypothesis describes the relationship between acquisition and learning, where acquisition leads to fluency and learning monitors correctness. 4) The Input Hypothesis states ideal language input focuses on meaning over form and emerges naturally from comprehensible input. 5) The Affective Filter Hypothesis posits that low anxiety, high motivation and self-confidence support comprehensible input.

1. Krashen SLA notions"Applications of Psycholinguistic Research to the Classroom"Stephen Krashen(1983)

2. Five hypotheses or notions:The Acquisition/Learning HypothesisThe Natural Order HypothesisThe Monitor HypothesisThe Input HypothesisThe Affective Filter Hypothesis

3. The Acquisition/Learning HypothesisThis states that there are twoways of learning a second language: Acquisition - occurs subconsciouslyLearning - which needs to be developedconsciously through education.

4. The Natural Order HypothesisKrashen believes that the evidence in this area shows that teachers should not follow any ordered pattern at all when teaching grammatical structures.

5. The Monitor HypothesisThis describes the relationships that exist between acquisition of language and learning of language.Acquisition is responsible for becoming fluent in a language while the learning process is only good for correcting or "monitoring" what has been acquired.Krashen presents three difficulties in monitoring:(a) not having enough time,(b) not being focused on what is correct, and(c) simply not knowing the formal rules.

6. The Input HypothesisThis states that ideal language input has three characteristics:(comprehensible input)(a) The focus is on the meaning, more than on how it is spoken.(b) Speaking emerges on its own when the learner’s understanding is good enough.(c) The best input is not grammatically sequenced.

7. The Affective Filter HypothesisLow anxiety, high motivation, and self-confidence are ideal.Comprehensible input: the idea, in short.Krashen suggests that having "comprehensible input" is the one and only common variable in all of these hypotheses. The implications for teaching are that programs should have the following traits.1) Understandable input, ideally both interesting and relevant to the learner.2) Speech emerges on its own and teachers should be tolerant of early errors in speech.3) Grammatical sequencing is not ideal.

8. Morpheme studies:Brown (1973) study of L1Dulay and Burt (1973, 1974) L2-ingPROGRESSIVE PLURAL COPULAAUXILIARY ARTICLEIRREGULAR PASTREGULAR PAST 3RD SINGULAR POSSESSIVEKrashen's (1977) 'Natural Order' for ESLThe Natural Order Hypothesis