"Object-Oriented Programming (OOP), in the past two decades, has become the most influential and dominant programming paradigm for developing large and complex software systems. With OOP, developers can rely on design patterns that are widely accepted as solutions for recurring problems and used to develop flexible, reusable and modular software. However, recent studies have shown that Objected-Oriented Abstractions are not able to modularize these pattern concerns and tend to lead to programs with poor modularity. Feature-Oriented Programming (FOP) is an extension of OOP that aims to improve the modularity and to support software variability in OOP by refining classes and methods. In this thesis, based upon the work of integrating an online tutor systems, ASSISTments, with other online learning management systems, we evaluate FOP with respect to modularity. This proof-of-concept effort demonstrates how to reduce the effort in designing integration code."