of the programming problem;(b) a narrative description of the process used by an expert to solve the problem, written so that a student can understand the expert's approach;(c) a listing of the expert's code;(d) study questions to provide practice in program design, problem solving, and analysis; and (e) test questions to assess students' understanding of the program solution. An example problem statement and summary of the design decisions for one of our case studies appears in Figure 1 and Sidebar 1.1 Our case studies explain and defend the decisions made by an expert to produce a solution to the problem at hand. Our narrative descriptions are similar to the discussions in the" Literate Programming" column in Communications (eg,[21]). They contrast effective and ineffective strategies for solving this problem and related problems, and also describe how expert programmers organize their programming knowledge. Competent programmers need both well-organized knowledge of a programming language and problem-solving skills. We refer to programming-specific versions of more general problem-solving ap-