Offering a rich, critical investigation of how technology can be used to strengthen and promote lesson study in both virtual and hybrid environments, this edited book presents insights into the numerous challenges as well as opportunities for supporting teachers’ and teacher educators’ professional learning in such a novel setting.

1. Teacher professional learning through hybrid lesson study 2. Potential of online experience of Lesson Study: Learning from the IMPULS efforts to provide research lesson observation online 3. Hybrid cross-cultural lesson study impacts teacher learning 4. What can online lesson study offer? Findings from an Australian – Japanese collaboration 5. An intercultural blended lesson study for teaching an in-service teacher education course: Collaboration between Singapore and Finland teacher educators 6. Analysing and facilitating collaboration in online lesson study 7. Online lesson study: Solving authentic problems of practice 8. Examining teacher professional learning: Transitions to online lesson study in STEM university contexts 9. Developing teacher educators’ researcherly disposition through lesson study in a virtual environment 10. Teachers’ awareness of classroom interactions in the hybrid distance education through Lesson Study 11. Brokering at the boundaries: A critical reflection on leading online lesson study 12. Changes in high school distance education science teachers’ pedagogical content knowledge during remote lesson study 13. Learning opportunities and problematic issues provided by online lesson study during a pandemic: Insights from WALS 2020 and 2021 14. Lesson study in a time of change: Working towards a new pedagogy in the digital age 15. Conclusion 16. Afterword: What to learn from and adopt, and what not-to-forget in the post pandemic world of lesson study and online professional learning

The chapters in this book provide informative descriptions of a wide range of lesson studies undertaken during COVID-19 and so in a context of rapidly developing digital and remote connections across participants and cultures. Readers interested in the research and practice of lesson study will find rich and critical reflection on how lesson study programs were adapted, new programs set up, the possibilities these opened up, and in some instances their affordances and constraints relative to face-to-face lesson study. The book is a welcome addition to the extensive literature on cross cultural lesson study, with inspiration and professional wisdom towards innovation and hybridization in a new digital era.Jill Alder, Professor of Mathematics Education, School of Education, at the University of the Witwatersrand, South Africa.Past President, International Commission on Mathematical InstructionHuang, Helgevold, Lang, Jiang and the contributing authors move our field forward from conceptualizing online/hybrid lesson study to highlighting and researching the innovative practices that show promise for LS. The book is helpful for practitioners who want to innovate LS to include digital technology that may afford opportunities for better access and equity for different stakeholders (including, students, teachers, math leaders, and LS facilitators) as well as researchers who want to consider theories and research methodology to propel this research forward. Scaling up and sustaining LS has always been a challenge and the promise of online/hybrid LS provides LS advocates with a lot of lessons learned from the contribution of the many leading LS researchers around the world. Jennifer Suh, Professor of Mathematics Education, Director, Center for Outreach for Mathematics Professional learning/Educational Technology George Mason University, USA.Board of Directors of National Council of Teachers of Mathematics, USA