This hypothesis argues that there is a natural order to the way second language learners acquire their target language. Research suggests that this natural order seems to transcend age, the learner's native language, the target language, and the conditions under which the second language is being learned. The order that the learners follow has four steps:
They produce single words.
They string words together based on meaning and not syntax.
They begin to identify elements that begin and end sentences.
They begin to identify different elements within sentences and can rearrange them to produce questions.