I retired in August 2022 as an associate professor from the University of Hong Kong, where I also had been associate dean (research) and created and led a stream of the Master of Education program focusing on the learning sciences—the designing Powerful Learning Environments specialism. This specialism targeted people with various professional backgrounds who were interested in how learning works.My research in the last 25 years had focused on Knowledge Building, an educational approach in which a class works as a community to investigate important questions on a theme on the curriculum. A key aspect of this work is dialogical discourse in a web-based environment called Knowledge Building. My team ‘s work focused on classroom implementation of the approach in primary and secondary schools, and on reflective assessment. Students used portfolios and other methods to self-evaluate and improve the progress of their community in its effort to learn about the theme. We used this approach from about Grade 4 in primary school through the end of high school, in subjects such as Geography, Science, and Chinese Literature. Through the years, our work was well-funded and received several prizes, including a "Most Usable Research" prize in 2006 from the NASA-funded Classrooms of the Future project, and a "Distinguished Paper" prize from the American Educational Research Association in 2015.Much of my teaching has been on research methodology and led to a book in 2022 (with co-authors Jin Mu, Crina Damsa, and Sydney Msonde, Learning Sciences Research for Teaching (Routledge). From 2017 through 2020 I was Editor-in-Chief (with Susan Yoon) of Journal of the Learning Sciences, and I was elected a Fellow of the International Society of the Learning Sciences in 2020.Since my retirement, I have taken op voluntary work (classroom) in an inner-city primary school on the outskirts of Rotterdam. The school is in one of the poorest districts in the Netherlands, and my work tries to tackle the problems with social justice and equity, which are so prominent now in education. But rather than as an academic, I do this “on the ground”, in a school where these issues play. It’s a great pleasure to be back in a school, working with teachers and children. I am currently writing a book for the general public on how learning works (in Dutch).Having more time for reading and such things, I have returned to my interests in theoretical physics, the history of science, and classical music.I am married to Carol Chan and live in Rotterdam and in Hong Kong.