The key purpose of marking and feedback is to promote learning and reduce the 'gap' between what students know or can do and what they need to know or do to make further progress. From January 2015 teachers will be marking work a little bit differently to how they may have marked it in the past.
All students have been given a copy of a document:
Students: TGS Feedback and Marking Policy
This has been written to help students understand the feedback they can expect from teachers, and to help them understand what they need to do in order to benefit from this feedback.