1. A system, comprising: a database for storing a plurality of documents, each of the plurality of documents associated with at least one user, wherein the database is configured to: receive a group of documents related to a course; receive at least one edit to one of the group of documents by at least one user; store the at least one edit and at least one time reference corresponding to the time during which the at least one edit was made; wherein sharing of content between each of the plurality of documents is restricted; a feature extraction module configured to: obtain a writing history for the at least one user associated with the one of the group of documents; determine a writing pattern associated with the one of the group of documents based on the writing history for the at least one user, the at least one edit, and at least one time reference; and generate a feature vector for the writing pattern.