## 2 Theoretical Background
These systems often require powerful computing hardware to run complex simulations, making them suitable for highly immersive experiences. In contrast, mobile VR solutions, such as Google Cardboard, use smartphones as display and processing units, making them more affordable but significantly less immersive [21; 22]. Thus, VR hardware is often categorized based on its level of immersion. Less-immersive VR systems, such as 360-degree videos and desktop VR applications, provide a limited sense of presence as users can observe the virtual environment but have restricted interaction capabilities [23]. In contrast, more-immersive VR systems utilize advanced HMDs with real-time motion tracking and haptic feedback, allowing for a deeper sense of embodiment and interactivity [24]. Research has demonstrated that high-immersion VR leads to greater learning gains by enhancing engagement and cognitive absorption [9]. However, it also presents challenges, such as increased cognitive load [25], high costs, and the need for specialized hardware [26], which may limit its widespread adoption in educational settings. Despite these challenges, VR's technological evolution continues to drive new educational applications. Studies have shown that immersive VR environments can significantly enhance the learning of procedural skills, such as surgical training [27] or the training of automotive painting techniques [28], as well as social skills, where authentic interaction scenarios are crucial for effective learning [29]. Hence, the application of VR in education spans various sectors, including vocational training, school education, and higher education. In vocational training, VR has been successfully implemented to enhance practical skill acquisition in fields such as medical training and industrial maintenance. Studies indicate that medical trainees who practice procedures in VR environments demonstrate improved accuracy and confidence in real-world applications [30; 31]. Similarly, VR-based training programmes in industrial settings allow learners to familiarize themselves with machinery and safety protocols without the risks associated with hands-on training [32; 33]. In school education, VR is particularly valuable for teaching complex scientific learning content by enabling students to visualize and interact with abstract phenomena that would otherwise be difficult to grasp [34; 35]. For example, research has shown that students who use VR to explore biological processes or physical simulations develop a deeper conceptual understanding compared to those using traditional instructional methods [36]. In STEM education, in particular, VR supports the visualization of abstract scientific concepts, such as molecular structures, physics simulations, or anatomical models, enabling learners to interact with complex phenomena in an intuitive and engaging manner. For example, [PERSON] and colleagues [35] highlight how immersive VR environments facilitate a deeper understanding of STEM topics by allowing students to explore virtual laboratories or conduct simulated experiments. Furthermore, VR technology can promote sustainable behaviour and climate change awareness among young learners [37]. In higher education, universities integrate VR into curricula to provide experiential learning opportunities. Virtual field trips, laboratory simulations, and interactive case studies allow students to engage with course material in ways that traditional classrooms cannot offer. The flexibility of VR-based learning environments also supports distance education by enabling remote students to participate in shared virtual spaces [38]. Additionally, VR has been applied in social sciences and humanities to simulate historical events, conduct virtual ethnographies, and support intercultural learning [39; 40]. These diverse use cases underscore VR's potential as a cross-disciplinary educational tool that supports both cognitive and affective learning objectives across educational contexts.