## 2 Materials and Methods
### Methods
In addition to the questionnaire, learners also participated in online focus groups in order to have a chance to further elaborate on the learning experience. They were split into two focus groups of 10 based on whether they had completed the ER alone or in a pair so as to facilitate conversation among participants with similar experiences. The questions that guided the discussion among the focus groups were developed based on the principles outlined by [PERSON] [60] (Appendix A, Table A3), who is recognised for his work in focus group interviewing. They aimed to promote conversation in order to create a social experience and allow participants to feel more comfortable in sharing their thoughts. Quantitative data were analysed using descriptive statistics in SPSS. Non-parametric tests were utilised due to the small sample size, the use of ordinal Likert scale data from questionnaires and the potential for non-normal distribution in order to provide a more reliable approach by not assuming data normality. More specifically, the Wilcoxon signed-rank test was used to determine the improvement in pre- and post-test scores within each group, and the Mann-Whitney U-test was used to compare pre- and post-test results between the two groups, as well as to compare questionnaire responses on learning experience across groups. The data from the focus groups were transcribed and organised based on the key themes of the research. The qualitative findings were reviewed alongside the quantitative data to provide a clearer understanding of how participants in the collaborative and individual conditions perceived the learning experience. Informed consent was obtained from all participants prior to their voluntary involvement in the study. They were orally informed about the study as well as of their right to withdraw at any point. More specifically, they were told that they would be participating online in a VR escape room activity in English that is part of a research project; thus, they would need to complete some tests and a questionnaire as well as participate in a focus group. All the information was presented in Greek, the participants' native language, to ensure that everyone understood what their participation would entail. Regarding confidentiality, data collected from participants, including pre- and post-test results and questionnaire responses, were anonymised by having them use unique 4-digit identification codes in place of names and using the first, middle or last two digits to report on the results. Implementation  
The implementation and evaluation of the escape room game took place in August 2024. Participants were asked to complete the online language level assessment test within a specific time limit, sending back their results with screenshots. Approximately 15 min before the ER sessions, they were sent the pre-test. A total of 15 live sessions were organised,namely 10 for each one of the individual participants in the control group and 5 for each one of the pairs in the experimental group. Immediately after participants completed the pre-test, they were sent a link to the first Frame. The communication was thereafter conducted through Frame VR. The briefing session with the instructions and the storyline video took place in this Frame, lasting approximately 15 to 20 min, depending on whether learners chose to customise their avatar as well as on their level of familiarity with technology. At the end of it, learners were directed to the ER through a link in the first Frame. All participants managed to escape within the appointed time frame of one hour and 15 min, with an average completion time of 71 min and 14 s. The teacher was present in the escape room in two modes, namely as a spectator and as an avatar, to be able to talk to participants without being seen. Individual participants completed the ER on their personal computers one at a time, with 3 pairs doing so on separate computers from different locations and 2 pairs using the same computer with a shared avatar (Figure 2).