Recently, in Indonesia, project-based learning (PjBL) has been used as an alternative approach in the teaching and learning process. Research on PjBL has been widely conducted in many countries at various levels. In most previous studies, PjBL was used to improve students' competence in certain math subjects. This study uses a case study research method to determine the effectiveness of PjBL at university in improving pre-service teachers' PCK. The research was carried out in 2022 involving fourteen mathematics education study program students selected by purposive sampling. The instruments used consisted of observation sheets, tests, and questionnaires. During the PjBL activity, participants were given a project to develop teaching materials for geometric transformation using certain teaching-learning strategies. The results of the study show that PjBL can improve students' PCK ability, although participants face several obstacles related to commitment to completing projects on time. Therefore, PjBL can be applied in the teaching-learning process to support professional mathematics teachers.

Immersion is an essential technical feature of immersive virtual reality (VR) environments, which can affect various learning and psychological outcomes. However, limited research has studied the impact of immersion via multiple mechanisms. In this study, we investigated the effects of immersion in a VR science learning environment using two different mechanisms, delivery format and sound stimuli, on various cognitive and psychological outcomes, including learning, cognitive load, self-efficacy, presence, enjoyment, and usefulness. Through a 2 (delivery format: immersive VR vs. Desktop VR) x 2 (sound stimuli: yes vs. no) design, one hundred and twenty participants experienced one of four versions of a VR tour on nature-based science learning, including an immersive VR (iVR) tour with or without sound, and a desktop VR (dVR) tour with or without sound. Both quantitative and qualitative data were collected. Results indicated that dVR groups rated significantly higher than the iVR groups on perceived learning, presence, self-efficacy, and usefulness, regardless of sound stimuli. However, neither immersion mechanism impacted knowledge retention, cognitive load, or perceived enjoyment. Meanwhile, all groups significantly improved self-efficacy after their condition-dependent VR experience. Qualitative data from participant responses provided additional perspectives on the quantitative findings. This research fills a gap in the limited existing literature by investigating immersion through multiple mechanisms in VR learning environments. The findings offer both theoretical and practical implications for researchers and practitioners.