Through real classroom interactions, deep mathematical analysis, and thoughtfully constructed problem strings, Pam Harris shows us how additive reasoning, multiplicative reasoning, and proportional reasoning are connected and figure-out-able. This is a must-read book for anyone who is striving to teach 6-8 math in a way that makes it make sense.

Peter Liljedahl, Simon Fraser University

Pam Harris makes the often-messy work of ‘reasoning over rules’ feel concrete and teachable—showing middle grade teachers how to move students beyond algorithm-following into real mathematical thinking. With clear learning progressions and practical routines like Problem Strings that help students see the math and make sense of relationships, this book is both a mindset shift and a ready-to-use roadmap.

John SanGiovanni, Howard County Public Schools

Pam Harris has written the book teachers have long needed. Fractions and proportional reasoning are the bedrock of algebraic thinking, and she makes both accessible with practical, research-grounded strategies. This book doesn’t just build understanding—it helps both students and teachers reclaim their confidence.

Pamela Seda

Pam Harris has done it again! This book is a masterclass in understanding and teaching middle school math concepts. Whether you are new to teaching middle school math and looking for a foundation to build from or a veteran looking to deepen your understanding, Developing Mathematical Reasoning is a must-have resource. The demonstrative visuals and sample dialogues provide a rich learning experience for the brains of all teachers.

Liesl McConchie, Math With the Brain in Mind

Developing Mathematical Reasoning: The Strategies, Models, and Lessons to Teach the Big Ideas in Grades 6–8 is an energizing read that helps middle school teachers move students beyond procedures to making sense of ratios, proportional reasoning, and operations through purposeful tasks. The book feels immediately usable for Grades 6–8 classrooms, offering practical moves that strengthen conceptual understanding while building coherence across the middle school math curriculum.

Carrie S. Cutler, University of Houston

The thing I’m most grateful for in this book is that on every page you can feel the heartbeat of a practitioner. While Harris has deep knowledge of educational research underneath everything she does, Developing Mathematical Reasoning is brimming with classroom-ready insights that will equip and enrich every teacher who picks it up and puts it into action.

Eddie Woo, University of Sydney

This is a powerful and practical guide for any teacher who wants their students to truly understand mathematics, not just perform it. Pam Harris, once again, challenges the idea that math is about memorizing steps and instead shows how students can build strategies through reasoning and relationships. The strength of this book is that it doesn’t just tell you what to believe; it shows you how to teach differently. The Problem Strings, the focus on making thinking visible, and the emphasis on multiplicative reasoning make this an incredibly valuable resource for the classroom. It’s the kind of professional learning that genuinely changes practice.

Chris Hogbin, Number Hive

Pam Harris and her team have done it again! This book brings concepts to life through engaging vignettes, real classroom examples, and visuals to help us make sense of the math. Grounded in sense-making, it invites deep thinking while remaining enjoyable to read. It’s an accessible, thoughtful resource that reflects her belief that math is figure-out-able. It also helps teachers connect middle school ideas to elementary models, strengthening coherence across grades.

Marria Carrington, Mount Holyoke College

Pam Harris’s use of Problem Strings transforms mathematics instruction from a linear sequence of isolated, bite-sized lessons into a series of conceptual landmarks, allowing students to navigate their own pathways toward understanding. For educators seeking to foster deeper mathematical thinking and to support students in modeling and articulating their reasoning, this book is an invaluable resource.

Leslie Mohlman, Alpine School District

This book is a must-read for teachers who are not only looking to build their content knowledge around traditionally difficult middle school content but also give actionable steps to fill the gaps in learning for students to be successful.

Lauren Gangel, Twin Cedars Community School District