Unit 3

Wrapping Up Addition and Subtraction within 1,000

Unit Goals

Unit Narrative

In this unit, students work toward the goal of fluently adding and subtracting within 1,000. They use mental math strategies developed in grade 2, and learn algorithms based on place value.

In grade 2, students added and subtracted within 1,000, using strategies based on place value, properties of operations, and the relationship between addition and subtraction. When students combine hundreds, tens, and ones, they use place-value understanding. When they decompose numbers to add or subtract, they rely on the commutative and associative properties. When students count up to subtract, they...

Section A

Section Goals

Section Narrative

Students begin this section by revisiting the idea of place value, reasoning about different ways to decompose numbers within 1,000, and using familiar strategies from grade 2 to add and subtract within 1,000.

From there, they progress toward more abstract addition strategies, but those that are still based on place value. To support this progression toward algorithms, students use base-ten...

Let’s represent numbers in different ways.

Let’s solve problems involving addition and subtraction.

Let’s add numbers within 1,000.

Let’s learn new ways to add.

Let’s learn another algorithm to add.

Let’s consider when to use algorithms and when to use other strategies to add.

Section A Practice Problems

to access Section Checkpoints.

Section A

Let’s represent numbers in different ways.

Let’s solve problems involving addition and subtraction.

Let’s add numbers within 1,000.

Let’s learn new ways to add.

Let’s learn another algorithm to add.

Let’s consider when to use algorithms and when to use other strategies to add.

Section B

Section Goals

Section Narrative

In this section, students analyze and use subtraction algorithms. They begin by using base-ten blocks and diagrams to subtract numbers. It is difficult to record regrouping with drawings, but students see algorithms as a helpful way to find differences.

As is the case with addition, students first make sense of a subtraction algorithm that uses expanded form, which allows them...

Let’s subtract numbers within 1,000.

Let’s learn a new way to subtract.

Let’s learn more about our first subtraction algorithm.

Let’s learn another algorithm to subtract.

Let’s think about subtraction algorithms in more detail.

Let’s consider when to use algorithms and when to use other strategies to subtract.

Section B Practice Problems

to access Section Checkpoints.

Section B

Let’s subtract numbers within 1,000.

Let’s learn a new way to subtract.

Let’s learn more about our first subtraction algorithm.

Let’s learn another algorithm to subtract.

Let’s think about subtraction algorithms in more detail.

Let’s consider when to use algorithms and when to use other strategies to subtract.

Section C

Section Goals

Section Narrative

In this section, students learn the conventions of rounding whole numbers to the nearest multiple of 10 or multiple of 100. This work relies on and reinforces their understanding of place value. Number-line diagrams are used to help students think about the multiple of 10 or multiple of 100 to which a given number is closest.

Students learn that when...

Let’s explore multiples of 100 and how other numbers relate to them.

For a given number, let’s find the closest multiple of 100 and the closest multiple of 10.

Let’s round to the nearest ten and the nearest hundred.

Let’s look for patterns in rounding.

Section C Practice Problems

to access Section Checkpoints.

Section C

Let’s explore multiples of 100 and how other numbers relate to them.

For a given number, let’s find the closest multiple of 100 and the closest multiple of 10.

Let’s round to the nearest ten and the nearest hundred.

Let’s look for patterns in rounding.

Section D

Section Goals

Section Narrative

In this section, students encounter more complex problems, think about the reasonableness of their answers, and use rounding to make estimates.

Students analyze tape diagrams that could represent the relationships in given situations and write corresponding equations to represent them. Previously, they worked with diagrams and equations with a ? or ___ to represent an unknown. Now, students interpret and...

Let’s decide if our answers make sense.

Let’s connect diagrams and equations to situations.

Let’s represent and solve problems.

Let’s represent and solve more problems.

Let’s make a wish list.

Section D Practice Problems

to access Section Checkpoints.

Section D

Let’s decide if our answers make sense.

Let’s connect diagrams and equations to situations.

Let’s represent and solve problems.

Let’s represent and solve more problems.

Let’s make a wish list.

to access End-of-Unit Assessments.

Navigation

Gradeband

Course

Unit

Settings

Audience

Assessment Access

Unit | Loading...

Wrapping Up Addition and Subtraction within 1,000

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

Section Goals

Section Narrative

Section D Practice Problems

Unit 3 Resources

About Unit 3

Other Resources

Section Goals

Section Narrative

Section C Practice Problems

Section Goals

Section Narrative

Section B Practice Problems

Section Goals

Section Narrative

Section A Practice Problems

Section Goals

Section Narrative

Section D Practice Problems