The purpose of this study is to introduce an instructional technology known as the "learning object". After a review of the literature, the designing steps of a learning object (LO) are tried to explain. As a learning object standard a few details are given about SCORM-Content Aggregation Model and common metadata elements. At the end, a case study about designing of a learning object with the subject of "Congestion Control in Computer Networks" is tried to give. The content is prepared in English and it contains 13 pictures within 22 him and 3 .exe files. The basic principles of the network congestion and the designed congestion control algorithms are given in the him pages. Simulators are used to show the working way of the related algorithms step by step. The LO design is made with an open source program RELOAD Editor, according to the ADL SCORM package. The designed LO has been tested on computer engineering students and positive feedbacks are received.