Much research in information retrieval (IR) focuses on optimization of the rank of relevant retrieval results for single shot ad hoc IR tasks with straightforward information needs. Relatively little research has been carried out to study and support user learning and engagement for more complex search tasks. We introduce an approach intended to improve topical knowledge of a user while undertaking IR tasks. Specifically, we propose to explore methods of finding useful and informative textual units (semantic concepts) within retrieved documents, with the objective of creating improved document surrogates for presentation within the search process. We hypothesize that this strategy will promote improved implicit learning within search activities. We believe that the richer document representations proposed in the paper would help to promote engagement, understanding and learning as compared to more traditional search engine document snippets. We propose a framework for holistic evaluation of our proposed document representations and their use in search.