“DIY 51: Teaching-Learning Materials [TLM] Mathematics (Part–1)” is a book specially designed for children in the primary classes. The primary objective of this book is to present Mathematics in a simple, engaging, and child-centered manner. It provides a collection of teaching-learning materials through which children can learn mathematical concepts while playing and exploring. The book has been developed in alignment with the vision of the National Education Policy (NEP) 2020, with a strong emphasis on Foundational Literacy and Numeracy (FLN). It offers children from Classes 1 to 3 opportunities to learn basic mathematical skills such as number recognition, shape identification, counting, addition–subtraction, and classification of objects in an experiential way. One of the major highlights of this book is that the TLMs suggested in it can be prepared using locally available, low-cost materials. This feature makes the book highly practical and accessible for teachers, enabling them to provide quality education even in resource-constrained environments. Thus, learning becomes not only theoretical but also practical and connected to real-life experiences. All the activities included in the book are based on the “Learning by Doing” approach. Activities like shape matching, counting through pictures, number identification, and addition tasks encourage active participation. These activities help foster curiosity, independence, and creativity among children, making the learning process more enjoyable and long-lasting. The author, Mr. Om Prakash Mishra, brings his rich experience and innovative practices in primary education into this book. His aim is to benefit both teachers and students by simplifying the teaching of Mathematics while inspiring educators to experiment with new methods. The upcoming Part–2 of this series will introduce even more advanced and engaging activities.