If the grading system is present ,for example if a student got grade A , he thinks that it is enough and do not improves .Moreover, grading system does not show a students talent..
* That depends on how easily you grade. If As are rare, then most students still see a need to improve. If you give everyone an A, then I would agree with you. The problem with marks is that the basis of difference between an 86 and an 87 is likely to be statistically insignificant, especially if what is being graded is subjective material, such as essays. It is likely that the student with the 87 would feel superior to the one with an 86, and that the student with an 86 would feel cheated out of a point. By using the broader grades, we are being more realistic in our marking. I can explain the difference between an essay which received an A and one which received a B (or even an A-). I can't explain logically the difference between one which received a 87 and one which received an 86. * to be honest i dont like either. The trouble with a grade is once a student had read the grade they wont read any other comments the teacher had made(especially if it is low). If improved learining is your goal avoid putting grades on studnents work unless you reallly have to ie for summative purposes.
Marks are no better for the same reason but also they do not mean anything. 68% for an essay tells me nothing. All it does is tell me it is not as good as 69% but better than 67%, useless information!!! especially when you consider the subjective nature of marking certain skills.
Comments on the studnets work are by far the best way of giving feedback and feedforward and will have a huge effect on improved