Teaching OO methodology in a project-driven CS2 course

Abstract

After we adopted an objects-first approach in CS1, we had to redesign our CS2 and data structures courses. This paper reports on our efforts to develop a project-driven CS2 course that expands on the object-oriented methodology introduced in the CS1 course. We focused on using collections and base classes in meaningful, large-scale projects helping students understand why these classes are important before concentrating on implementation in the subsequent data structures and algorithms course. We also introduce the concepts of design patterns and frameworks. This paper focuses on the OO methodology developed in the course; a companion paper [6] deals with pedagogical issues in using our approach. Background Our Objects-First Approach in CS1In the CS1 course we followed the "BlueJ approach" using the Barnes and Kolling textbook [1] and the BlueJ Integrated Development Environment (IDE). The textbook focuses on object-oriented programming as contrasted with a focus on programming language syntax. In many of the programming projects, parts of the implementation involve advanced concepts and remain "under wraps" as other components are developed. We adopted a similar approach in our CS2 course where students extended built-in classes without worrying about the class implementation. Projects in the CS2 CoursesTurner and Zachary [3] report that using a single project for the entire course not only teaches students about algorithms and data structures but also allowed the students to apply a variety of software engineering techniques. Ghafararian [5] reports on a similar effort, but he included four smaller programs in addition to the course long project. Copyright is held by the author/owner(s). OOPSLA'05, October 16-20, 2005, San Diego, California, USA. ACM 1-59593-193-7/05/0010. Newhall and Meeden [2] use a search engine project to introduce a variety of data structures, including priority queues, binary search trees, hash tables and graphs. This project lasted the second half of the CS2 course.Rebelsky and Flynt [4] also used a project that lasted the second half of the course but used group development where each group worked on a different component of a single classwide project. This was an ambitious effort that contains both benefits and risks. A major risk is the "weakest link" problem.Other problems involved effective communication both within and between groups and overestimating the amount of work that could be accomplished in half a semester. Why Our Approach is UniqueThe approaches referenced above include large projects in the CS2 course, but we have gone further by letting the needs of the projects drive the topics covered in the course. This is most evident in our choice of a textbook [7] that is used as a reference book rather than the traditional plowing through a textbook in sequential order.The lecture sections involved active program development to support the week's lab activity. A wireless keyboard and mouse was passed from student to student as programs were developed with the guidance of the in...

Scaffolding for multiple assignment projects in CS1 and CS2

“…[13], [14]). A variety of approaches and mechanisms have been proposed to emphasize object-oriented design ( [1], [2]), classical data structures and algorithms ( [10], [12]), team work ( [13]) or combinations of these and other factors (e.g. [9], [11], [14]).…”