“Usability rules the Web!” (Nielsen, 2000). It is very easy to recommend that a Web-learning application should be usable, but it is often a difficult design objective to achieve. We believe that usability can be achieved by bringing the interface closer to the user’s way of thinking and working. It is important to design applications that are based on the mental models of users in order to achieve high usability. Designing high usability can be achieved by adopting user interface design models and an object-oriented approach. We have developed a methodology—the Web user object modelling (WUOM) method—to guide designers to develop Web learning applications that have high usability. This chapter describes the WUOM method to develop a Web application for learning circuits based on WUOM. Evaluation of the Web application shows that it has high usability.