Are Black Boxes Transparent?— High School Students' Strategies of Using Abstract Data Types

Abstract

For the last ten years the concept of abstract data types (ADTs) has been introduced to Israeli high school students who take the courses “Logic Programming” and “Introduction to Artificial Intelligence” as part of their Computer Science (CS) curriculum. We developed an instructional model designed to introduce ADT as a formal CS concept and as a tool for developing computer programs. To implement the abstract data types, we used “black boxes.” Here we describe our research whose aim was to assess the cognitive aspects of using ADTs as tools for knowledge representation and problem solving by different student populations. Our research findings indicated that many students' perceptions of the ADT concept were compatible to its formal CS definition, and they used black boxes transparently to develop Prolog programs. However, there were also students who adopted their own strategies for using ADTs: a) using ADTs only as a graphical description to organize data and knowledge; and b) using “ADT black boxes” in alternative ways, while violating the principle of information hiding—duplication, rewriting, and externalization. The findings also indicated that “ADT black boxes” were beneficial in helping beginners to develop correctly written Prolog programs.