Categorizing and ameliorating generalization-specialization design mistakes in an intermediate programming class

Creating complex generalization-specialization relationships is challenging for students who are new to object-oriented design. The current work seeks to categorize student design mistakes in inheritance modeling involving multiple inheritance and a larger number of super and sub-classes than students routinely encounter in introductory inheritance-related code examples. Student responses to a task requiring the creation of an inheritance lattice has led to a preliminary categorization of major error types and an assessment of relative frequencies of the errors. Examples of student work that illustrate various errors are included. This article concludes with a discussion of how these examples can be used in active learning exercises.