The World-Wide-Web is a well-established source of resources for different applications and purposes including the support to learning and teaching tasks. The notion of Learning Object (LO) was specifically designed for sharing digital learning materials over web-applications enabling repositories of LOs. But, the extension of such repositories is rather small compared to the Web, and some of these repositories are domain-dependent. LOs typically provide some educational metadata describing the content. However, the WEB hosts hundreds of thousands of web-pages with educational content but with no educational metadata. Generic search engines provide the best current support to sieve such educational web-pages. But such present systems are not educational focused, so they may not pick instructional features that the users want or need for their educational task. We study a web-based retrieval method for using the Web as a repository of educational resources. Our proposal is a new structured scoring method named Educational Ranking Principle (ERP). ERP analyses the suitability of a web-page for teaching a concept in a specific educational context. Our approach shows a superior accuracy performance than Google, TFIDF and BM25F. The results of our experiment using MAP and P@1 undoubtedly confirm the improvement of ERP when compared to all the baselines (with a p-value less than 0.05). Moreover, ERP is the only method where our results have statistical support for higher accuracy than Google for all the four accuracy measures we use in this study.