## 4 Discussion
### Limitations and Future Research  
The limitations of this study presented in this paper include most notably a small sample size and a cross-sectional design. Therefore the study results must not be generalised. Next, the assessment of the quality of the learning experience and the quality of interaction with the social robot NAO as a facilitator of the planning poker activity was based primarily on the quantitative data. In order to get a deeper understanding of the possible effects of applying a social robot as a facilitator of collaborative learning activities, future studies should include more qualitative data (e.g., through in-depth interviews), design longer interventions (longitudinal studies), and aim for larger samples. Furthermore, the evaluation study presented in this paper did not employ an experimental design and did not compare different conditions, such as human and robotic facilitators. Future studies should assess the benefits and drawbacks of social robots compared with other types of human and nonhuman facilitators. Finally, another limitation of the study was the lack of pre- and post-testing, which could have been valuable for capturing knowledge and skills of students before and after playing the planning poker with NAO. Future studies should address these limitations. Further possible directions for future research include taking the diversity of participants and of facilitators' tasks into consideration when designing the facilitation of collaborative learning with social robots. Furthermore, different styles of facilitation could be explored in future studies.  
The following supporting information can be downloaded at: [[https://github.com/Humanoid-Robots-as-Edu-Assistants/Planning_Poker](https://github.com/Humanoid-Robots-as-Edu-Assistants/Planning_Poker)]([https://github.com/Humanoid-Robots-as-Edu-Assistants/Planning_Poker](https://github.com/Humanoid-Robots-as-Edu-Assistants/Planning_Poker)), accessed on 27 February 2023. This is the Open Source repository with the final version of the game-based application \"Planning poker with NAO\", published on the Github page of the Communications Lab at Berlin University of Applied Sciences.  
This research received no external funding.  
The study did not require ethical approval since no more than minimal risk was identified. The study was performed in accordance with the ethical standards laid down in the guidelines by the German Ministry of Science and Education titled\" Research Ethics Principles and Testing Procedures in the Social and Economic Sciences\", [[https://www.konsortswd.de/wp-content/uploads/RatSWD_Output9_Forschungsethik.pdf](https://www.konsortswd.de/wp-content/uploads/RatSWD_Output9_Forschungsethik.pdf)]([https://www.konsortswd.de/wp-content/uploads/RatSWD_Output9_Forschungsethik.pdf](https://www.konsortswd.de/wp-content/uploads/RatSWD_Output9_Forschungsethik.pdf)), accessed on 27 February 2023. The ethical aspects were carefully considered in the research design and informed consent was received from all participants. The data security and privacy policy was strictly followed based on the Regulation (EU) 2016/679 of the European Parliament and the council from 2016 on the protection of individuals with regard to the processing of personal data and free movement of data flows, [[https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:32016R0679](https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:32016R0679)]([https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:32016R0679](https://eur-lex.europa.eu/legal-content/DE/TXT/PDF/?uri=CELEX:32016R0679)), accessed on 27 February 2023.