Research on Educational Metaverse (Edu-Metaverse) has developed into an active research field. Based on 310 academic papers published from 2004 to 2022, this study identifies contributors, scientific cooperations, and research themes using bibliometrics, social network analysis, topic modeling, and keyword analysis. Results suggest that Edu-Metaverse has gained increasing attention in academia since 2019. Countries/affiliations located in the same regions are close partners in scientific cooperation. By jointly interpreting topic modeling and keyword analysis results, this study reveals eight main themes in the field of Edu-Metaverse: 1) metaverse-based physical education, 2) metaverses-supported simulations for collaborative problem-based learning (PBL) in health/medical education, 3) three-dimensional virtual learning environment-supported art appreciation and creation in art education, 4) metaverse-enabled laboratories for STEM education, 5) language and 21st-century skill development through metaverse-supported immersive language learning, 6) metaverse for developing autism children' social communication abilities, 7) virtual world metaverse-supported gameful experience-based education, and 8) quantitative research on Edu-Metaverse focusing on learners' experience. We also identified challenges and directions needing further attention: 1) data security and privacy protection, 2) balance between the real world and virtual world identities, 3) preparing instructors for Edu-Metaverse, and 4) assessment of higher-order thinking competencies in Edu-Metaverse-based PBL. This work helps facilitate researchers' and practitioners' understanding of Edu-Metaverse research and raises their awareness of research frontiers and future directions.