Ontologies play an important role as knowledge domain representations in technology-enhanced learning and instruction. Represented in form of concept maps they are commonly used as teaching and learning material and have the potential to enhance positive educational outcomes. To ensure the effective use of an ontology representing a knowledge domain it needs to be validated. In this paper a previously presented validation methodology for concept maps is exemplified. Two different types of concept map validity are distinguished, referring to the correctness of the concept map's content (content validity) and to the applicability of the concept map for its designated purpose (application validity), like its use in intelligent tutoring. To demonstrate the usefulness of the two validation types and approaches, they are illustrated by an empirical study. The content validity of a concept map on elementary geometry has been investigated by comparing it with empirically collected criterion maps through similarity measures. To demonstrate application validity an approach utilising methods of Knowledge Space Theory for predicting problem-solving behaviour has been applied. The obtained results show appropriate content validity as well as application validity for the given concept map and argue for the practical relevance of the proposed validation framework.