When teachers learn, they listen to people talk about teaching and they sometimes talk with each other about teaching, but they very rarely *do* teaching. But for teachers to develop expertise in complex skills, they need opportunities to practice.  At the MIT Teaching System Lab, we develop practice spaces: learning environments inspired by games and simulations that let teachers rehearse for and reflect on important decisions in teaching. Our primary digital platform is Teacher Moments, a mobile web app that immerses participants in vignettes of classroom life through video, text, and images, and then calls on participants to improvisationally respond to difficult situations through recorded audio and text. The system has an extensible AI integration that allows scenario designers to include classifiers that detect participant behaviors and speech acts and respond with feedback and supports. For a technology system to support practice-based teacher education, it needs to seamlessly integrate into teacher education programs, provide evidence of effectiveness, and work across a wide variety of diverse contexts. As a case study, we'll explore the integration of digital clinical simulations into an open online course offered on the edX platform, Becoming a More Equitable Educator: Mindsets and Practices. 

Justin is an associate professor of digital media in the Comparative Media Studies/Writing department at MIT and the director of the Teaching Systems Lab. He is the author of Failure to Disrupt: Why Technology Alone Can’t Transform Education, and the host of the TeachLab Podcast. He earned his doctorate from the Harvard Graduate School of Education and was the Richard L. Menschel HarvardX Research Fellow. He is a past Fellow at the Berkman-Klein Center for Internet and Society. His writings have been published in Science, Proceedings of the National Academy of Sciences, Washington Post, The Atlantic, and other scholarly journals and public venues. He started his career as a high school history teacher, and coach of wrestling and outdoor adventure activities.