This paper presents the adaptation model used in NUCLEO, a pilot e-learning environment that is currently being developed at the Complutense University of Madrid. The NUCLEO system combines two approaches grounded in the constructive pedagogical stream, the Computer Supported Collaborative Learning and the Problem Based Learning, with the engaging and immersive formats of the videogames. It provides a futurist scenario in which students (represented by avatars and organized in small teams) have to collaborate to solve a learning “mission” following the mechanics of a classical role based play. In order to increase the efficiency of the collaborative work and to reduce the teacher’s workload, NUCLEO applies user modeling techniques to the students’ learning strategies, considering a simplified framework of Vermunt’s model for learning styles. The model determines how the system brings together students whose learning strategies are complementary to build up collaborative and ...