The research team @fise group (Activity Theory in Formal and Informal Science Education) of the University of Ioannina inaugurates with this book the series "Socio-cultural dialogues in STEAM Education" (Science, Technology, Engineering, Arts and Mathematics). The main goal of the book is to create a new agenda for the Teaching of Natural Sciences with a theoretical framework of Cultural-Historical Activity Theory. The theory is analyzed from Vygotsky to Engestrom and the international ISCAR community. The practice is intertwined in four integrated researches and one in progress, which develop a new methodology in the design of educational programs for the Natural Sciences. Innovative actions "open" the school to the local community, the museum, the ecosystem, and the digital learning environment. The book is addressed to specialists, researchers, and especially educators. At the same time, it proposes a new epistemological glossary for the terms activity, mediation, tool, object, perezhivanie, practice vs praxis. The innovation of the book is related to other contemporary trends such as critical theory, the transformative mind, social change, as well as the 17 goals for sustainable development (Agenda 2030).