Position paper for OOPSLA '96 workshop
"Teaching and Learning Object Design in the First Academic Year"

Case studies

A case study describes a programming problem, the process used by an expert to solve the problem, and one or more solutions to the problem. Case studies emphasize the decisions encountered by the programmer and the criteria used to choose among alternatives. Questions interspersed in the presentation help engage the learners in the case study, allowing them to "think along" with the expert by making predictions, helping with parts of the solution, or analyzing alternatives. More comprehensive questions ask students to modify the solution, apply the ideas to new problems, detect bugs in related problems, and reflect on their own methods for solving problems. Two collections of case studies are Designing Pascal Solutions: A Case Study Approach (W.H. Freeman, 1992) and Designing Pascal Solutions: Case Studies Using Data Structures (W.H. Freeman, 1996), both by Michael Clancy and Marcia Linn.

Case studies engage students in a kind of "apprenticeship" with an expert programmer. Linn and Clancy ("The Case for Case Studies of Programming Problems", Communications of the ACM, March 1992) elaborate on their advantages, which include the following:

• They model efficient ways to organize programming knowledge.
• They help students construct techniques and strategies that reduce or postpone the complexity of program design and development.
• They guide students to apply program design skills to large, complex problems and to learn context-dependent design strategies.
• They encourage students to reflect on completed solutions, comparing them to one another.
• They stimulate students to recognize their own strengths and weaknesses (in order to guard against the latter).
• They make large programs accessible to students, and thus give students a better picture of the nature of "real programming".
• They form the basis for assessment of a student's ability to design, understand, analyze, modify, and debug code that is both educational and effective.
• They provide a vehicle for active rather than passive learning, and exploration in teams.

Teaching Object Design: What needs help?

We've been teaching object-oriented programming (using Scheme and C++) in the first two courses for CS majors here at Berkeley for several years. A number of aspects of object design seem to cause students difficulty:

• overcoming a bias toward procedural design;
• separating functionality among a collection of collaborating objects;
• recognizing opportunities for reuse of existing classes;
• instrumenting and testing objects;
• identifying patterns among computation components.

Case studies can help. I'm working on developing cases appropriate for use by introductory students, and will report on my progress at the workshop.

Biography

Mike Clancy is Senior Lecturer and Coordinator of Lower-Division Courses in the Computer Science Division at the University of California, Berkeley.

He is co-author of the two case study collections listed above, and has long been a missionary for the case study approach to teaching. As a researcher, he focuses on various aspects of education in programming and computer science, including curriculum, laboratory management, and uses of technology.