With the increasing volume of learning resources on the Web, the need for automatic mechanism for extracting knowledge has become more critical. The aim of this paper is to propose an approach that can automatically construct directed semantic relationships between concepts to help teachers or students efficiently retrieve appropriate knowledge from the Web. The most distinctive characteristic of this approach is its support for constructing with expandable query. This characteristic addresses the problem of users with varying backgrounds. Working with semantically similar expanded terms allows them to filter out irrelevant terms and focus on corresponding contexts. In addition, we design two learning tasks to show that how this the constructed DSR graph can be used to scaffold students' semantic reasoning. The case study suggests relevant benefits of applying semantic technologies in an educational context.