In recent years, the fast growth of Web pages and the constant evolution of internet technologies have lead to a significant increase in the number of pedagogical resources. Thus, the indexing and search problems have become crucial. To overcome this problem, it was proposed to use information coming from the norms and standards of educational metadata. However, this solution does not solve completely the problem. Previously, traditional information retrieval systems rely on indexing by keywords for representing pedagogical resources and queries content. This process, based on lexical matching, allows selecting pedagogical resources based on keywords shared with the query, which can reduce the accuracy of search results if the meaning of common words in the query and in the pedagogical resources is different. To overcome this issue and provide a more sophisticated search, adding semantics becomes necessary. Semantic Indexing offers a representation by the meaning of words in order to find pedagogical resources semantically relevant to the user request. We present in this paper the choice of the indexing approach used for the complementary educational resources. The main objective is to integrate this approach in the warehouse model that aims on one hand to store the complementary pedagogical resources, and on the other hand to help the user fill in the description fields of these resources.