We present a low-cost, UDL-grounded instructional approach to teaching the central dogma of molecular biology in an undergraduate course. The design integrates a kinesthetic MDF jigsaw with PLA 3D-printed molecular models, multimodal accessibility assets (Braille process cards, captioned/narrated micro-lectures, QR-linked resources), and an educational chatbot that delivers formative, rationale-seeking feedback on student-generated case studies. In a pilot cohort (N=18; matched n=10), learning scores increased from 8.2 (pre) to 9.6 10 (post) on a paired test, t(9)=2.91, two-tailed p =0.017,95% CI for ¿ M=1.4:[0.31,2.49]; variance decreased from 3.07 to 0.27, indicating greater response consistency. Standardized effects were large (paired d (z)=0.92; Hedges' g 0.98). Perception data showed impact/usefulness =69.7 / 100 (collaborative work =94) and engagement =75.5 100 (self-regulation/strategic thinking =89). Grounded in Universal Design for Learning and research on serious games and chatbots in education, the approach is scalable and transferable to related life-science topics, providing a transferable framework for inclusive STEM education. We outline threats to validity (sample size, instrumentation) and a replication plan with pre-registered analyses and component ablation to benchmark the relative contribution of the tactile kit, multimodal media, and chatbot.
