Book excerpt: This book explains how young children develop mathematically in their earliest years and shows the support and teaching needed by adults to accelerate their progress and attainment, helping them master mathematical concepts and skills. The practical guidance has been carefully developed over a number of years and is based on research undertaken with primary schools in Sheffield as part of the 'Talk for Maths Mastery' initiative. It recognises that children’s mathematical development is embedded within child-led play and connected to deeper levels of thinking and wider dispositions for learning. Maths is happening everywhere at any moment; we just need to keep an open mind, open eyes, and listen. Including case studies, links to practice and reflective questions, the chapters reveal what mastery orientation looks like from the children’s perspective in their learning and covers: children’s serve and return conversational talk mathematical babies and their developmental momentum schematic patterns of thinking mathematical mark-making child-led play problem solving creative and critical thinking how adults can support children’s mathematical talk, thinking and mastery This book will help all early years practitioners and teachers working with children throughout the EYFS and KS1 build their understanding, knowledge, experience and confidence of engaging in early mathematics.