Exploratory Study on Accuracy of Students' Mental Models of a Singly Linked List

This Research Full Paper presents a study on the accuracy of computer science (CS) novices' mental models about linked lists in the C programming language. In CS, learning abstract fundamental concepts that require students to understand memory management can be very difficult and lead to misunderstandings that carry on into the advanced topics. This is especially true for linked lists data structures because they serve as a bridge to understanding more advanced data structures. Therefore, it is important to understand how students think about linked lists for improving teaching and learning. Exploratory research on mental models in CS is not as well-known as in other disciplines, such as Psychology, Education, Chemistry, Physics, and Mathematics. Since CS is based on abstract concepts like in Chemistry, Physics, and Mathematics, we believe the CS education community can benefit from more research on mental models and student reasoning, especially in fundamental areas such as data structures and algorithms. Hence, we conducted 2-hour semi-structured, think-aloud interviews with 11 undergraduate students to uncover the accuracy of their mental models, including their conceptual and procedural understanding, about singly linked lists. Our results suggest that none of the participants have an accurate mental model of a singly linked list, after learning about them and implementing them in their data structures course. Students struggle with expressing their conceptual understanding in their verbal responses to interview questions, while their scores for the coding questions are much better. Overall, the majority of students have a good procedural understanding of how to use the components of a linked list and implement the operations on a singly linked list, but most students cannot express their conceptual understanding of the components in a singly linked list. The results from this research suggest that educators need to spend more time covering linked lists in their data structures courses and make sure that students understand how their prerequisite knowledge of pointers and memory management integrate with the new knowledge about linked lists.