Massive online open courses' (MOOCs') students who use discussion forums have higher chances of finishing the course. However, little research has been conducted for understanding the underlying factors. One of the reasons which hinders the analysis is the amount of manual work required for annotating posts. In this paper, we use machine learning techniques to extrapolate small set of annotations to the whole forum. These annotations not only allow MOOC producers to summarize the state of the forum, but they also allow researchers to deeper understand the role of the forum in the learning process.