The rise of robotics and the internet of things (IoT) has led to more interdisciplinary computing opportunities. With the real-life application of these new technological affordances across disciplines, more universities are engaging students in practical, hands-on interdisciplinary design. This case study aims to train two undergraduates from different disciplines to apply robots and IoT in instructional design to benefit young language learners. The two undergraduates, one majoring in engineering and the other majoring in applied foreign languages, voluntarily participated in this interdisciplinary project-based learning (iPjBL). By creating an emulated environment that connects educational robots and tangible objects, the two designers achieved a theme-based instructional game design. The researchers assessed the quality of their instructional design, compared their design processes, and identified three factors that led to differing designer perspectives-(a) disciplinary training, (b) prior experience, and (c) design beliefs. These different perspectives can be used to help design training for instructional designers from various disciplines on how to apply robots and IoT-based tangible objects in language education. Challenges faced by the two designers included insufficient cross-disciplinary expertise, existing knowledge and skill gaps, and the need to redefine design beliefs to achieve better design outcomes. Issues and needs related to interdisciplinary learning were addressed and synthesized into essential steps to guide future instructional design that incorporates robots and IoT-based tangible objects. Overall evaluation of the interdisciplinary learning outcome using the First Principles of Instruction model demonstrated that iPjBL can provide valuable learning for instructional designers from different disciplines.