The online learning environment provides the opportunity for remote groups of students to interact with instructors and each other. Most web based learning platforms facilitate asynchronous online discussions between participants. These discussion forums are designed to replicate the face to face tutorial setting and provide a medium for the expression and development of student ideas. In this paper, an online discussion between twenty-eight teachers retraining in the field of mathematics will be analysed using the SOLO taxonomy. The analysis will focus on the capacity of web based learning environments to foster deep learning through the careful design of discussion tasks.