The following link will bring you to an article developed by Writing Services at the University of Toronto. The purpose of this article is to give instructors some ideas on developing and then marking written assignments.

Abstract- "Your comments on student papers can do more than defend the grade you give. Annotations can teach ways of thinking in your discipline as well as helping students become better writers. Fortunately, the most helpful ways of responding to students' writing also save time and frustration. These guidelines are distilled from good practice among experienced instructors. Choose the points that suit your circumstances."

Website link: http://www.utoronto.ca/writing/comm.html