Ontologies have emerged as one of the most popular and widely accepted tools in technology enhanced learning supporting knowledge representation and learning content creation. In this paper, we are interested in Semantic Web technologies and ontologies to deliver peer assessment as part of Inquiry based learning (IBL) environment. Introducing peer assessment can be a way to force students to take the responsibility to make a judgment about the actual contribution of each of their peers and to enrich their knowledge by assessing the work done by other learners. In particular, we focus on Problem Based Learning (PBL) scenarios, as a specific case of IBL scenarios. Delivery of peer assessment in these environments is often based on the use of social media, to enable collaboration and communication between learners. We aim to deliver formative peer assessment activities as part of PBL activities adapted to learner specific context, profile and progress in the learning process. Detailed scenarios descriptions are proposed and semantic models are specified and presented to enable the delivery of peer assessment activities. A heavyweight peer assessment ontology is described as part of an inquiry learning ontology and linked to other semantic models to support the peer assessment activity in IBL environments. A Semantic Web framework is finally proposed to integrate the defined semantic models. Keywords: inquiry based learning, problem based learning, peer assessment, scenarios, social media, semantic web, linked data, ontologies.