Communicative role of trees in Algorithms and Data Structures Textbooks
Illustration Practices in Computer Science Textbooks
Péter Aszalós (TU Delft - Electrical Engineering, Mathematics and Computer Science)
M. Dhume – Mentor (TU Delft - Electrical Engineering, Mathematics and Computer Science)
M. Skrodzki – Mentor (TU Delft - Electrical Engineering, Mathematics and Computer Science)
R.R. Venkatesha Prasad – Graduation committee member (TU Delft - Electrical Engineering, Mathematics and Computer Science)
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Abstract
Tree-based illustrations are widely used in Algorithms and Data Structures (ADS) textbooks to communicate hierarchical relationships. This study investigates how tree-based illustrations are used and what communicative functions they serve across different topics and textbooks.
A comparative qualitative thematic analysis was conducted on three ADS textbooks. Illustrations of general trees, binary trees, binary search trees, AVL trees and heaps were analysed using a coding framework derived from Levin's functional taxonomy of illustrations, Mayer's multimedia learning theory and Duval's theory of semiotic representation. The analysis focused on signalling and register shift.
The results revealed two main patterns. First, signalling techniques such as highlighted paths, arrows and geometric shapes were frequently used to communicate algorithmic behaviour that is not directly visible in tree structures. These techniques often accompanied register shifts between visual and verbal representations. Second, the textbooks differ substantially in their visual conventions, reflecting different approaches to communicating information through illustrations.
The study concludes that tree-based illustrations function as communicative tools that support both structural and procedural understanding, while shaping how readers connect visual and verbal representations.