To understand a living system, such as a tree, in an ecologically systemic way involves more than simply reducing the tree down to its parts or by analyzing the tree from part to whole. Not only does one need to study the tree’s leaves, stems, branches, trunk, root system, and its interaction with the environment but from many vantage points to make sense of how each part exists in dynamic relationship with the others as an integrated system. The same is true about the purpose of this book. It is not meant to be a recipe for how to teach mathematics well or to serve as simply a descriptive account of a teaching practice. It is in essence, a systemic exploration into the embeddedness and co-emergence of theory and practice in mathematics teaching. This book is ideal for undergraduate and graduate courses in mathematics education and curriculum studies. With its up close and contextual forms of data and a variety of interpretive methods used for the analyses, this book is highly suitable for courses in research. The audience includes professors, teacher educators, and in-service teachers who are interested in ecological theories and how these inform mathematics teaching and learning. “This book allows the reader to see children and their teacher really grappling with important mathematical ideas. Thom reveals how children occasioned by evolving promptings within the classroom might live mathematics through the invocation of hypotheses and the exploring of these, which lie for me, at the heart of contemporary mathematical culture. Thom successfully brings together embodied and dynamical ideas of knowing with current thinking on mathematics knowing and understanding. While the book has deep theoretical bases, Thom has written and developed it in ways that make the practices of mathematics knowing vividly evident and presents new ideas for living out mathematics teaching.” -- Thomas Kieren, University of Alberta “Thom offers a vibrant introduction to how an eco-complex approach to mathematics teaching might feel. Playing across individual and collective levels of knowing, she presents “living” accounts of the emergence of mathematical knowledge. She challenges us to attend to the complexities of subtle and seemingly mundane shifts in mathematical understanding as she confronts us with key issues in both responsive and participatory research. Few researchers have managed to speak so compellingly to what it might mean to carry an eco-complex sensibility in the classroom” -- Brent Davis, University of Calgary