Unit 2

Adding and Subtracting within 100

Unit Goals

Unit Narrative

Previously, students added and subtracted numbers within 100 using strategies they learned in grade 1, such as counting on and counting back, and with the support of tools, such as connecting cubes. In this unit, students add and subtract within 100 using strategies based on place value, the properties of operations, and the relationship between addition and subtraction.

Students begin by using any strategy to find the value of sums and differences that do not involve composing or decomposing a ten. They are then introduced to base-ten blocks as a...

Section A

Section Goals

Section Narrative

In this section, students find the value of unknown addends using methods that are based on place value and are introduced to base-ten blocks. Students continue to rely on the relationship between addition and subtraction to solve problems involving differences.

Students begin by solving Compare story problems. They use any methods and tools that make sense to them—including diagrams and...

Let’s solve Compare problems with greater numbers.

Let’s find values that make the equations true.

Let’s solve story problems.

Let’s play games to practice adding and subtracting.

Section A Practice Problems

to access Section Checkpoints.

Section A

Let’s solve Compare problems with greater numbers.

Let’s find values that make the equations true.

Let’s solve story problems.

Let’s play games to practice adding and subtracting.

Section B

Section Goals

Section Narrative

In this section, students subtract one- and two-digit numbers from two-digit numbers within 100. To reason about differences of two numbers, students use methods based on place value, base-ten blocks and diagrams, and properties of operations. The numbers here require students to decompose a ten when subtracting by place.

Students also make sense of different representations of subtraction by place,...

Let’s subtract 1-digit numbers from 2-digit numbers.

Let’s compare ways to subtract.

Let’s subtract two-digit numbers.

Let’s compare different ways to subtract.

Let’s find the difference in our own way.

Let’s play games to practice adding and subtracting.

Section B Practice Problems

to access Section Checkpoints.

Section B

Let’s subtract 1-digit numbers from 2-digit numbers.

Let’s compare ways to subtract.

Let’s subtract two-digit numbers.

Let’s compare different ways to subtract.

Let’s find the difference in our own way.

Let’s play games to practice adding and subtracting.

Section C

Section Goals

Section Narrative

This section allows students to apply their knowledge to solve story problems that involve addition and subtraction within 100. The story problems include all types—Add To, Take From, Put Together/Take Apart, and Compare—and have unknowns in all positions.

Previously, students worked with diagrams that represent Compare problems. Throughout this section, students also make sense of diagrams that could represent Put...

Let’s solve story problems.

Let’s make sense of diagrams and solve story problems.

Let’s make sense of equations and solve story problems.

Let’s solve story problems and share our thinking with others.

Let’s decide if estimates make sense.

Let’s use diagrams to make and solve our own story problems.

Let's think about how to run a store.

Section C Practice Problems

to access Section Checkpoints.

Section C

Let’s solve story problems.

Let’s make sense of diagrams and solve story problems.

Let’s make sense of equations and solve story problems.

Let’s solve story problems and share our thinking with others.

Let’s decide if estimates make sense.

Let’s use diagrams to make and solve our own story problems.

Let's think about how to run a store.

to access End-of-Unit Assessments.

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Adding and Subtracting within 100

Unit Goals

Unit Narrative

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section B Practice Problems

Section Goals

Section Narrative

Section C Practice Problems

Unit 2 Resources

About Unit 2

Other Resources

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section B Practice Problems

Section Goals

Section Narrative

Section C Practice Problems