Explaining design patterns through one application

The benefits of using design patterns have been widely acknowledged by experienced software professionals. However, it´s not intuitive for novice programmers to recognize appropriate patterns and apply them properly. This paper reports an experience of teaching design patterns to seniors. In that class, the requirements of an interactive quiz environment were described as if the clients requested them in multiple stages. Each stage requested additional features that were not included in the previous stage. As the requirements were presented to the students, design patterns were introduced to the students accordingly. In particular, the emphasis was to demonstrate how various design patterns could be used to minimize the impact Of requirement changes. This practice helped students see the process of recognizing appropriate design patterns. For each pattern selected, this paper presents both the original class diagram as given by the Gang of Four and the matching class diagram that illustrates the application of the pattern.