1. Introduction
This paper attempts to critically examine the overall usefulness of the various focuses of teacher feedback and the nature of teacher commentary in relationship to students' revision. Revising the final product is necessary because it enables students to correct their own grammatical mistakes and reorganize their essays in a coherent manner. It is my contention that error correction and greater attention to discourse features play an important role in improving the writing skills of students.

2. Teacher feedback on grammar
2.1 Effective or ineffective?
The debate over the usefulness of teacher feedback on grammar has caused ripples of concern in the educational world. There is no lack of studies supporting the contention that 'error treatment does not help students master the second language and can even interfere with their acquisition process' (Gebhard, 1997: 124). For example, Truscott's review article provides a fascinating insight into the ineffectiveness of teacher feedback on grammar. Truscott claimed that none of the research work done on grammar feedback to students' writing in both L1 and L2 domains proved to be useful or effective and that grammar correction in fact has harmful effects on students. This review article further states that although students prefer grammar correction, 'this does not mean that teachers should give it to them (Truscott, 1996: 359). Krashen and Terrell also argue that teachers should not treat errors directly. They regard errors as signs of naturalistic developmental processes (Richards & Rogers, 2003: 182). Willis belongs to the same camp and he believes that 'learners have to go through a process which involves making mistakes before they can produce appropriate forms spontaneously and without conscious attention' (2003; 7).
Unlike Truscott, some Universal Grammar (UG) linguists suggest that second language learners may need to be given some explicit information about what is not grammatical in the second language (Lightbown & Spada, 2001: 37). Not only do teachers need to provide information about what is grammatical, they should also provide direct evidence of what is ungrammatical (Ellis, 2003: 67). In other words, teachers need to give feedback on grammar. A recent study on teacher feedback also finds that grammar feedback can reduce error ratio (Tsang, Wong & Yuen, 2000: 317). Balancing these contrasting perspectives, we can safely conclude that the theoretical justification for giving feedback on grammar is far from strong. But in Hong Kong (HK) many principals and English language teachers strongly believe that teachers need to give feedback on grammar. Because many HK students do not use English in their daily communication (Li & Chan, 2000: 335), they tend to depend heavily on explicit teaching of grammatical rules and teacher feedback on grammatical errors. School administrators hope that teacher feedback on grammar could play an important role in helping students develop their self-monitoring and self-correcting techniques.

2.2 Error treatment
If teachers decide to give feedback on grammar, they should exhibit much subtlety in treating grammatical errors. Brown suggests that error treatment and focus on language forms appear to be most effective when incorporated into a communicative, learner-centered curriculum, and least effective when error correction is a dominant pedagogical feature, occupying the focal attention of students in the classroom (1994: 219). In a communicative classroom, teachers can use some accuracy-based activities to create a positive link between teacher feedback and error reduction. Unlike fluency-based activities, accuracy-based activities tend to place emphasis on correct language forms.
Besides, teachers should discern the difference between global and local errors. According to Brown, global errors need to be corrected in some way since the message may otherwise remain garbled (1994: 221). When teachers give feedback on grammar, they are advised to underline the mistakes. Direct correction should be avoided because it might not benefit students' writing (Tsang, Wong & Yuen, 2000: 323). Moreover, direct correction may stifle students' attempts at production.

3. Teacher feedback on grammar and content
Some recent studies suggest that teachers might be shifting their feedback-giving priorities and responding more to students' ideas and organization than they did in the past (ibid, 319). Another study found that the teachers under study responded mostly to the content of students' writing and at the same time indicated students' major patterns of error by some in-text underlining and comments. This combination of commentary proved to be useful in helping students make substantial and effective revisions (ibid). Some local teachers also realize that simultaneous grammar and content feedback can force students to attend to language forms and the shaping and restructuring of their ideas. In HK, the research conducted by Tsang, Wong and Yuen reveals that content feedback is effective in improving grammar score (vocabulary, language use and mechanics) (ibid). Very often, feedback on content and organization can force students to re-think and re-arrange their ideas in a coherent manner.

4. Revising the final product
Since teachers of English in HK are under great pressure to correct students' errors (Li & Chan, 2000: 348), they may not have time to carefully read the revised essays submitted by their students. But there is a growing appreciation that a revision of the final product can force students to correct their grammatical mistakes and re-arrange their ideas in a logical manner. In particular, teacher feedback on content can play a crucial role in drawing learners' attention to the importance of discourse features in textual organization.
In order to encourage students to revise their final products, Ur suggests that teachers should not grade the first drafts. Teachers just need to give feedback to students. The students then knows that, if he or she incorporates all the corrections and suggestions, there is a very good chance of getting a high mark, and the procedure is immediately rewarding as well as learning-valuable (Ur, 2003: 256).

5. Conclusion
Although some scholars have given the thumbs down to grammar feedback, local teachers and school administrators still favor this marking method. It seems unlikely that these scholars will be able to find enough evidence to convince HK teachers to press the stop button on grammar feedback. Apart from giving grammar feedback, some local teachers also give content feedback to students. Several studies find that simultaneous content and grammar feedback could help students improve their writing skills (Tsang, Wong & Yuen, 2000: 319). Besides, students are advised to revise their final products.

The End

References

Brown, H.D.(1994) Principles of language learning and teaching. New Jersey: Prentice Hall Regents.

Ellis, R.(2003) Second language acquisition. Oxford: OUP.

Gebhard, J. G.(1997) 'Interaction in a teaching practicum,' IN Richards, J. & Nunan, D. (eds.), Second language teacher education. Cambridge: CUP, p. 118-131.

Li, D. & Chan, A.(2000) 'Form-focused negative feedback: toward a pedagogically sound model of remedial instruction,' IN Li, D. Lin, A. & Tsang, W.K. (eds.), Language and education in postcolonial Hong Kong. Hong Kong; Linguistic Society of Hong Kong, p. 333-351.

Lightbown, P. & Spada, N.(2001) How languages are learned. Oxford: OUP.

Richards, J. & Rogers, T.(2003) Approaches and methods in language teaching. Cambridge: CUP.

Truscott, J.(1996) 'Review article: The case against grammar correction in L2 writing classes,' IN Language learning. 46, p. 327-369.

Tsang, W. K., Wong, M. & Yuen, H.K. (2000) 'Feedback to writing: Focusing on grammar, or content, or both,' IN Li, D. Lin, A. & Tsang, W. K. (eds.) Language and education in postcolonial Hong Kong. Hong Kong: Linguistic Society of Hong Kong, p. 327-332.

Ur, P.(2003) A course in language teaching. Cambridge: CUP.

Willis, D.(2003) Rules, patterns and words. Cambridge: CUP.