## 5 Limitations and Future Work Recommendations  
The study provides several insights but also comes with certain limitations. The sample size was relatively small, from two higher education institutions, and focused on a specific field, thus limiting the generalizability of the findings. Future research should involve larger, more diverse participant groups across different scientific disciplines to validate and extend these results. Another suggested research direction would be comparing the effects of an online immersive CSI module with a respective attendance-based lesson or unit. Additionally, the study did not assess the short- and long-term effects of VR training on knowledge retention and skill transfer. Longitudinal studies are needed to evaluate how well learning outcomes are maintained over time and to determine the ideal frequency and duration of VR training for lasting educational benefits. Further research could also explore (a) the effectiveness of VR in other scientific fields, such as chemistry, physics, and environmental science, as well as (b) the perceptions of teachers who use 3 VLEs systematically for teaching and learning. To this end, personalizing the instructional approach to match individual learners' needs and preferences should also be a focus for future investigations. Finally, future research could examine the sustainability of 3 DVLEs in terms of their reusability and adaptability with easy-to-use authoring tools for updating the simulation with different scenarios and learning materials. **Author Contributions:** Conceptualization, A.E., S.D. and W.K. ; methodology, A.E. and S.D. ; software, W.K. ; validation, A.E. and W.K. ; formal analysis, S.D. ; investigation, A.C.; resources, B.Y. ; data curation, A.E. and S.M. ; writing--original draft preparation, S.M. and A.C.; writing--review and editing, S.M. and I.H. ; visualization, S.D. ; supervision, A.E. ; project administration, S.K. ; funding acquisition, I.H. All authors have read and agreed to the published version of the manuscript. **Funding:** This research was funded by the European Commission, grant number 585772-epp-1-2017-1 ps-eppka2-cbbe-jp (project TESLA--Virtual Reality as an Innovative and Immersive Learning Tools for Higher Education Institutions in Palestine). **Institutional Review Board Statement:** The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Ethics Committee of the University of Patras (protocol code 549 on 30 April 2018). **Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study. **Data Availability Statement:** The data used to support the findings of this study are available from the corresponding author upon request. **Acknowledgments:** This paper reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein. Also, the authors thank all team members from all institutions involved in the project. The first author thanks [PERSON] and [PERSON] for their efforts during the development phase. **Conflicts of Interest:** The authors declare no conflicts of interest. **Appendix A. Data Collection Instrument**