This mathematics book is written for teachers, both prospective and practicing. It is suitable for those less comfortable with mathematics, as well as those who already have a stronger mathematical background. Research shows that knowledge of traditional, formula-based approaches is not enough for effective conceptual classroom teaching. In this book, teachers will learn the reasoning behind the methods, developed in ways that will also make sense to intermediate and early secondary students. Many ideas and activities introduced here are directly transferable to classroom use, while concepts are developed using visual models and representations, manipulatives, reasoning, and with deep connections to other concepts. These methods support better thinking, learning, and understanding for all students. In addition, these visual and active approaches are also much better aligned with Indigenous ways of thinking and knowing, a critical benefit for societies striving for decolonization.