## Design Principles

### Developing Conceptual Understanding and Procedural Fluency

Each unit begins with a pre-assessment that helps teachers gauge what students know about both prerequisite and upcoming concepts and skills, so that teachers can gauge where students are and make adjustments accordingly. The initial lesson in a unit is designed to activate prior knowledge and provide an entry point to new concepts, so that students at different levels of both mathematical and English language proficiency can engage productively in the work. As the unit progresses, students are systematically introduced to representations, contexts, concepts, language and notation. As their learning progresses, they make connections between different representations and strategies, consolidating their conceptual understanding, and see and understand more efficient methods of solving problems, supporting the shift towards procedural fluency. Practice problems, when assigned in a distributed manner, give students ongoing practice, which also supports developing procedural proficiency.

### Applying Mathematics

Students have opportunities to make connections to real-world contexts throughout the materials. Frequently, carefully-chosen anchor contexts are used to motivate new mathematical concepts, and students have many opportunities to make connections between contexts and the concepts they are learning. Many units include a real-world application lesson at the end. In some cases, students spend more time developing mathematical concepts before tackling more complex application problems, and the focus is on mathematical contexts. Additionally, a set of mathematical modeling prompts provide students opportunities to engage in authentic, grade-level appropriate mathematical modeling.

### Use of Digital Tools

These curriculum materials empower high school teachers and students to become fluent users of widely-accessible mathematical digital tools to produce representations to support their understanding, solve problems, and communicate their reasoning.

Digital tools are included when they are required by the standard being addressed and when they make better learning possible. For example, when a student can use a graphing calculator instead of graphing by hand, use a spreadsheet instead of repeating calculations, or create dynamic geometry drawings instead of making multiple hand-drawn sketches, they can attend to the structure of the mathematics or the meaning of the representation.

Lessons are written with three anticipated levels of digital interaction: some activities require digital tools, some activities suggest digital tools, and some activities allow digital tools. In a few cases, activities may prohibit digital tools if they interfere with concept development.

In most cases, instead of being given a pre-made applet to explore, students have access to a suite of linked applications, such as graphing tools, synthetic and analytic geometry tools, and spreadsheets. Students (and teachers) are taught how to use the tools, but not always told when to use them, and student choice in problem-solving approach is valued.

When appropriate, pre-made applets may be included to allow for students to practice many iterations of a skill with error checking, to shorten the amount of time it takes students to create a representation, or to help students see many examples of a relationship in a short amount of time.

### The Five Practices

Selected activities are structured using Five Practices for Orchestrating Productive Mathematical Discussions (Smith & Stein, 2011), also described in Principles to Actions: Ensuring Mathematical Success for All (NCTM, 2014), and Intentional Talk: How to Structure and Lead Productive Mathematical Discussions (Kazemi & Hintz, 2014). These activities include a presentation of a task or problem (may be print or other media) where student approaches are anticipated ahead of time. Students first engage in independent think-time followed by partner or small-group work on the problem. The teacher circulates as students are working and notes groups using different approaches. Groups or individuals are selected in a specific, recommended sequence to share their approach with the class, and finally the teacher leads a whole-class discussion to make connections and highlight important ideas.

• Provide experience with a new context. Activities that give all students experience with a new context ensure that students are ready to make sense of the concrete before encountering the abstract.
• Introduce a new concept and associated language. Activities that introduce a new concept and associated language build on what students already know and ask them to notice or put words to something new.
• Introduce a new representation. Activities that introduce a new representation often present the new representation of a familiar idea first and ask students to interpret it. Where appropriate, new representations are connected to familiar representations or extended from familiar representations. Students are then given clear instructions on how to create such a representation as a tool for understanding or for solving problems. For subsequent activities and lessons, students are given opportunities to practice using these representations and to choose which representation to use for a particular problem.
• Formalize a definition of a term for an idea previously encountered informally. Activities that formalize a definition take a concept that students have already encountered through examples, and give it a more general definition.
• Identify and resolve common mistakes and misconceptions that people make. Activities that give students a chance to identify and resolve common mistakes and misconceptions usually present some incorrect work and ask students to identify it as such and explain what is incorrect about it. Students deepen their understanding of key mathematical concepts as they analyze and critique the reasoning of others.
• Practice using mathematical language. Activities that provide an opportunity to practice using mathematical language are focused on that as the primary goal rather than having a primarily mathematical learning goal. They are intended to give students a reason to use mathematical language to communicate. These frequently use the Info Gap instructional routine.
• Work toward mastery of a concept or procedure. Activities where students work toward mastery are included for topics where experience shows students often need some additional time to work with the ideas. Often these activities are marked as optional because no new mathematics is covered, so if a teacher were to skip them, no new topics would be missed.
• Provide an opportunity to apply mathematics to a modeling or other application problem. Activities that provide an opportunity to apply mathematics to a modeling or other application problem are most often found toward the end of a unit. Their purpose is to give students experience using mathematics to reason about a problem or situation that one might encounter naturally outside of a mathematics classroom.

A note about standards alignments: There are three kinds of alignments to standards in these materials: building on, addressing, and building towards. Oftentimes a particular standard requires weeks, months, or years to achieve, in many cases building on work in prior grade levels. When an activity reflects the work of prior grades but is being used to bridge to a grade-level standard, alignments are indicated as "building on." When an activity is laying the foundation for a grade-level standard but has not yet reached the level of the standard, the alignment is indicated as "building towards." When a task is focused on the grade-level work, the alignment is indicated as "addressing."

A note about mathematical diagrams: Everything in a mathematical diagram has a mathematical meaning. Students are sense makers looking for connections. The mathematical diagrams provided in activities were designed to include only components with mathematical meaning. For example, while it is not uncommon to see arrows on the ends of a graph of a function, the arrows add no mathematical meaning to the graph. Arrows are typically used to imply a sense of direction, but a graph of a function is representation of all the points that make the function true, so there is no direction to imply. It is also possible for students to infer meaning that isn't there, such as assuming the arrows mean the function continues forever in a specific direction. While this idea works for linear functions, it does not work with functions whose graphs curve or are periodic.