As the area of Data Structures and Algorithms (DSA) is crucial in computing science, the materials for teaching and learning DSA are often reused in related courses in such programs as Computer Science, Information Technology and Business Computer. This paper presents an approach to the design of Reusable Learning Objects (RLO) using XML Topic Maps (XTM) to organize a wide range of course materials, including programming codes, Java applets for data-structure demonstration, and algorithms visualization tools. The approach is intended to create a highly interactive Web-based learning and exploration environment, in which students can learn through experimentation. The RLO design applies Topic Mapping for classifications of learning resources in two dimensions. In one dimension, the Concept Space is defined as the knowledge representation in form of a DSA ontology. In the other dimension, the Engagement Taxonomy with six different levels of engagement in combination with Visualization materials is used to describe the Media Space.