adult second language learners can develop second language learning. One method is learning, a conscious study of the forms of language. The other method is acquistion, or just picking up a language the way children do without conscious attention to forms. Krashen further argues that acquisiton is far more beneficial in terms of producing fluent, natural communication in another language. Krashen also asserts that learning cannot change into acquistion.
Note: Learning can be a confusing word because in the acquisition-learning hypothesis it has a very precise meaning: a conscious study of rules and forms. However, learning is also used in a more general sense of becoming more proficient or knowledgable in something. So for example, in the sentence: