This book helps teacher designers better understand the roles of technology in education, the key design perspectives of a technology-mediated learning environment (TMLE), the design considerations for each perspective, and the design processes of a TMLE. This book presents a generic conceptual framework, called Pedagogical, Social and Technical design (PST), to illustrate the main design perspectives of the TMLE and their relationship. It also describes a pragmatic design approach, the educational design research approach, for teacher designers to easily follow when they are designing TMLEs. This book also demonstrates two application examples using the PST framework as a design tool to design a blended synchronous learning environment and as an analytical tool to evaluate the educational affordances of an information and communication technology tool.