Learning Object (LO) is one of the main research topics in the e-learning community in the recent years. In this context, granularity is a key factor for LO reuse. This paper presents a methodology to define the learning objects granularity in the computing area as well as a case study in software testing. We carried out five experiments to evaluate the learning potential from the produced learning objects, as well as to demonstrate the possibility of LO reuse. The results show that LOs promote the understanding and application of the concepts. In addition, the set of LOs identified through the proposed methodology allowed its reuse in different contexts.