On the Quality of Examples in Introductory Java Textbooks

Abstract

Example programs play an important role in the teaching and learning of programming. Students as well as teachers rank examples as the most important resources for learning to program. Example programs work as role models and must therefore always be consistent with the principles and rules we are teaching. However, it is difficult to find or develop examples that are fully faithful to all principles and guidelines of the object-oriented paradigm and also follow general pedagogical principles and practices. Unless students are able to engage with good examples, they will not be able to tell desirable from undesirable properties in their own and others’ programs. In this article we report on a study in which experienced educators evaluated the quality of object-oriented example programs for novices from popular Java textbooks. The evaluation was accomplished using an online checklist that elicited responses on the technical, object-oriented, and didactic quality of examples. In total 25 reviewers contributed 215 reviews to our dataset, based on 38 example programs from 13 common introductory programming textbooks. Results show that the evaluation instrument is reliable in terms of inter-rater agreement. Overall, example quality was not as good as one might expect from common textbooks, in particular regarding certain object-oriented properties. We conclude that educators should be careful when taking examples straight out of a textbook.