In this work, we propose a model for building Virtual Learning Environment (VLE) where intelligent virtual agents play the role of tutors and are expected to help a human user to follow a procedural scenario with predefined learning outcomes. Our model provides the agents with a cognitive architecture to make sound reasoning on its knowledge base. The agent is materialized in front of the user as an Embodied Conversational Agent (ECA) that communicates and interacts with her/him in a credible human-like manner. Our implemented model is then tested in a concrete pedagogical scenario for learning blood analysis procedures in a biomedical laboratory.