Instructional materials matter. 

Over the past decade, high-quality instructional materials (HQIM) have become increasingly central to mathematics teaching and learning. They are more detailed, more widely used, and more influential than ever. Materials are now expected not only to organize content, but also to support ambitious instruction, anticipate student thinking, guide discussion, and support differentiation. 

But materials do not teach. Teachers do. 

Much of the field still operates as if materials can drive instruction on their own—often framed in terms of “implementation” or fidelity. That framing misses something fundamental about teaching. 

Teaching is not the execution of a script. It is contingent, interactive work shaped by students, context, time, and in-the-moment judgment. What happens in classrooms depends not only on what materials contain, but on how teachers interpret, use, adapt, and respond while working with them. 

Implementation and enactment 

In discussions of instructional materials, the field often uses the language of implementation—whether materials are used as intended, with fidelity, and without deviation. 

This framing suggests that materials contain a plan for instruction that can be carried out more or less correctly. 

But this is not how teaching works. 

Even when teachers aim to use materials closely, what happens in the classroom is shaped by far more than the written guidance. Teachers are constantly interpreting tasks, deciding what to emphasize, responding to student thinking, adjusting pacing, and navigating time and context. 

Enactment names this reality. 

Materials provide resources—tasks, representations, explanations, and suggestions—but they do not determine what happens. What unfolds depends on how teachers take them up and how students respond in the moment. 

For example, a lesson may include a discussion prompt intended to surface a particular mathematical idea. In one classroom, the teacher may press on that idea, ask follow-up questions, and connect student responses to the lesson goal. In another, the teacher may move quickly past the discussion to stay on pace. In another, a student’s unexpected idea may shift the direction of the conversation entirely. 

The same materials are being used. But what happens instructionally is different. 

Materials shape teaching. They do not determine it.  

For example, a curriculum may include detailed guidance for anticipating student thinking or using a particular representation. But that guidance may be spread across sidebars, unit overviews, or separate resources. In the flow of planning—or in the moment of teaching—teachers may not see it, may not have time to use it, or may prioritize other parts of the lesson instead. 

In this case, the support exists. But it may not meaningfully shape what happens in practice.