2025 ASEE Annual Conference & Exposition

Introducing algorithmic data structure concepts to middle school students poses a unique challenge due to their complexities and reliance on code-specific syntax. Aiming to simplify this process, we adapted a tangible Binary Search Tree (BST) activity from the CS Unplugged curriculum to promote an experiential understanding of the BST data structure. This paper presents our iterative approach to developing this activity, first through describing our preliminary qualitative findings and then by proposing a mixed-method study to formalize our inquiry with quantitative data.

We implemented two versions of the BST activities in week-long summer coding camps for middle school students during June and July 2023. Our qualitative observations and field notes from these implementations informed future design considerations. In our first iteration, students drew BSTs with chalk on pavement, and they struggled with the inflexibility of chalk diagrams. In our second iteration, students created BSTs with manipulable notecards and physical connectors made from string, and a spy-themed narrative was added to increase student engagement. In this second iteration, we observed that students often bypassed systematic tree traversal by visually scanning for targets, potentially undermining conceptual understanding of BST efficiency.

Building on our qualitative findings, we propose a mixed-method study of middle school students in informal, summer STEM learning environments. Pre- and post-surveys will examine student self-reported engagement and enjoyment. An activity quiz will assess if students can identify correctly-structured BSTs and perform simple operations on a BST. Interviews with implementing educators will provide information on student behavior, questions, and misconceptions during the activity.