Post-Lecture Interactive Environments for Conceptual Learning: A Randomized Comparison of Mixed Reality and Tangible Instruction in Undergraduate STEM Education
Developing conceptual understanding in engineering requires learners to connect spatial reasoning with abstract representations, yet lecture-based instruction often provides limited support for this process. Interactive learning environments, including mixed reality (MR) and tangible tools, may help students revisit difficult concepts through action, feedback, and visible system response. This pilot randomized study compared two post-lecture interventions, an immersive MR application and a tangible Engineering Toolkit, with lecture-only instruction in undergraduate solid mechanics. Twenty-four participants completed a baseline assessment, a common lecture, and a post-instruction knowledge test; participants in the interactive conditions also completed usability and learner-experience measures. Learning outcomes were analyzed using ANCOVA with baseline knowledge as a covariate and were supported by normalized learning gains. Instructional modality had a significant effect on post-test performance, $F(2, 20) = 3.60$, $p = .048$, partial $\eta^2 = .263$. Both interactive conditions outperformed lecture-only instruction in planned contrasts. MR showed the highest normalized learning gain ($g = .57$), whereas the tangible toolkit showed higher usability and learner confidence. In the MR condition, virtual reality sickness symptoms measured via the Virtual Reality Sickness Questionnaire remained low before and after the intervention, suggesting that the MR application was well-tolerated by participants. These results suggest that post-lecture interactive environments may support immediate conceptual learning while offering different modality-specific strengths that require larger, time-matched follow-up studies.