The main purpose of this work is to develop an intelligent tutor system coupled to a robotics virtual laboratory, in order to offer a tutored virtual learning environment. The student model is the main component of this intelligent tutoring systems (ITS). We propose a probabilistic relational model to characterize the students, so the domain can be represented in terms of entities, their properties, and the relations between them. In this way we obtain a compact and natural representation, which can be learned from data, by combining the results from the students interaction with the virtual laboratory and the models for similar students.