One of the most rapidly evolving e-services is e-Learning, that is, the creation of advanced educational resources that are accessible on-line and, potentially, offer numerous advantages over the traditional ones like intelligent access, interoperability between two or more educational resources and adaptation to the user. The driving force behind these approaches is the definition of the various standards about educational metadata, that is, data describing learning resources, the learner, assessment results, etc. The internal details of systems that utilize these metadata is still an open issue since these efforts are primarily dealing with "what" and not "how".

Under the light of these emerging efforts, we present CG-PerLS, a knowledge based approach for organizing and accessing educational resources. CG-PerLS is a model of a web portal for learning objects that encodes the educational metadata in the Conceptual Graph knowledge representation formalism, and uses related inference techniques to provide advanced, personalized functionality. The model allows learning resource creators to manifest their material, client-side learners to access these resources in a way tailored to their individual profile and educational needs, and dynamic course generation based on fine or coarse grained educational resources.