In John Truscott and Angela Yi-ping Hsu’s recent research (2008), teachers’ corrections indeed help learners reduce their errors: the revised manuscripts of students who received it showed significantly more improvement in accuracy than those of students who did not receive it. They did some experiment on students’ error corrections in writing exercise. From this experiment, it presents that error correction does help students reduce their errors on the writing on which they receive the corrections, and that the effect is substantial.