Looking at what principles can guide us in the teaching of grammar. Both Hedge and Thornbury (2001) give us
some worthy answers. Hedge (2000) considers that the presentation of grammar to learners should facilitate learning
in many ways: It can provide input for noticing output and accurate forms of English; it can present high-frequency
grammatical items explicitly to speed up learning; it can provide information about the communicative use of
language structures by contextualizing them in spoken and written form; it can give information implicitly through
exposure to examples or explicitly through instruction on the stylistic variation of language form. Thornbury (2001)
summarizes some rules of thumb about the teaching of grammar