On the surface, it is entirely reasonable to make the analogy. after all, every child , given a normal developmental environment, acquires his native language fluently and efficiently; moreover, he acquires it "naturally" without special instruction, though not without notable conscious effort and attention to language. however, the direct comparisons such as those that have been made must be treated with caution. there are dozens of salient differences between first and second language".
there are quite a good number of theories, observations, and research that support the notion that learning the second language is like learning the first language. traditional language teaching practice, as enshrined in grammar-translation method, for example, ran directly counter to this view.
the basic principle of the direct method of learning language, in which the teachers are supposed to teach without using material and without using the mother tongue, are derived from a conscious attempt to simulate natural conditions of language learning or, in other word, to encourage the second language learning in the same way as the first language is learnt.