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What's in a Linked List? A Phenomenographic Study of Data Structure Diagrams

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2021 ASEE Virtual Annual Conference Content Access


Virtual Conference

Publication Date

July 26, 2021

Start Date

July 26, 2021

End Date

July 19, 2022

Conference Session

Undergraduate Students' Development of Computational and Programming Skills

Tagged Division

Educational Research and Methods

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Paper Authors


Morgan M. Fong University of Illinois, Urbana-Champaign

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Morgan M. Fong is a Ph.D. student in the Department of Computer Science at the University of Illinois, Urbana-Champaign and an NSF Graduate Research Fellow. Prior to starting her Ph.D. Morgan completed her B.A. in Computer Science at the University of California, Berkeley. She is broadly interested in how people learn computer science with a focus on creating inclusive learning environments.

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Seth Poulsen University of Illinois at Urbana-Champaign Orcid 16x16

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Seth Poulsen is Ph.D. student in Computer Science at University of Illinois at Urbana-Champaign and an NSF Graduate Research Fellow. Before beginning his Ph.D. he completed a Bachelors degree in Mathematics at Brigham Young University and worked as a Software Engineer at His research interests include using technology to help students learn to write mathematical proofs, educational data mining, and computing and math education more broadly.

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Geoffrey L. Herman University of Illinois at Urbana-Champaign Orcid 16x16

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Dr. Geoffrey L. Herman is a teaching associate professor with the Deprartment of Computer Science at the University of Illinois at Urbana-Champaign. He also has a courtesy appointment as a research assistant professor with the Department of Curriculum & Instruction. He earned his Ph.D. in Electrical and Computer Engineering from the University of Illinois at Urbana-Champaign as a Mavis Future Faculty Fellow and conducted postdoctoral research with Ruth Streveler in the School of Engineering Education at Purdue University. His research interests include creating systems for sustainable improvement in engineering education, conceptual change and development in engineering students, and change in faculty beliefs about teaching and learning.

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Diagrams in data structures provide a valuable context for untangling the relationship between spatial ability and persistence in computer science, but we have little understanding about what kinds of diagrams are used. Spatial ability is a strong predictor of success in computer science, and data structures tend to rely on spatially oriented language and tasks (e.g., nodes moving, pointers pointing). However, beyond these examples, we lack a formal understanding of how diagrams are drawn and used for instruction and how spatial ability may be related to these diagrams. In this paper, we present an initial study using phenomenographic methods to explore how YouTubers draw and animate linked list diagrams in instructional videos. YouTube™, while not a traditional resource, provides access to instructors who come from all over the world, increasing the variety of our data set. Through inductive coding, we developed a code book to describe how the diagrams were crafted and how diagrams were manipulated to illustrate insertion. We found that every YouTuber used diagrams, indicating their prevalence. YouTubers also used consistent language (e.g., “head,” “tail,” “node”) and similar talking points (e.g., comparison to arrays). However, there was considerable variance in how linked lists were represented. Representational choices seemed to change in response to instructional goals or tasks. Finally, we discuss possibilities for standardizing diagrams moving forward, what may be spatial about these diagrams, and the implications of uncommon codes.

Fong, M. M., & Poulsen, S., & Herman, G. L. (2021, July), What's in a Linked List? A Phenomenographic Study of Data Structure Diagrams Paper presented at 2021 ASEE Virtual Annual Conference Content Access, Virtual Conference. 10.18260/1-2--38052

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