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Activity 1

Standards Alignment

Building On

Addressing

Building Toward

Instructional Routines

Number Talk

Materials

None

Activity Narrative

The purpose of this activity is for students to reason about subtraction and write another subtraction expression to complete a partially-completed Number Talk routine. If there is time, students can facilitate their Number Talk with another group. Students are given three expressions and prompted to think of ways that they could be evaluated mentally. They then write a fourth expression, the value of which they could use similar reasoning, or the values of the first three expressions, to find.

MLR8 Discussion Supports. Synthesis: Create a display of the task. As students share their expression, annotate the display with the expression and its connection to the third expression in the Number Talk. For example, if students share , write “100 less than 399” next to the expression.
Advances: Reading, Representing

Launch

Groups of 2–4
“Here are three expressions like the kinds you might see in a Number Talk.”

Activity

“How would you find the value of each expression, without writing? For each expression, think of at least two ways. Then share your thinking with your group.”
Reiterate to students that they are to consider how someone might reason about each difference, rather than only find the value.
4 minutes: independent work time
4 minutes: small-group discussion
“Write one more expression that could go with the other three expressions to complete a Number Talk routine.”
4 minutes: small-group work time
Monitor for groups who consider the following strategies in writing their expression:
- Adjust the 399 to a different number, but keep the 500.
- Leave the 399, but adjust the 500.
- Adjust both the 500 and the 399, but create a problem that can be reasoned, as in previous expressions.
Identify groups, who chose different strategies, to share in the Activity Synthesis.

Here are 3 subtraction expressions.

Think of at least 2 different strategies you can use to find the value of each difference mentally.
Write 1 more subtraction expression whose value can be found using 1 of the strategies you thought of.

Activity Synthesis

Select groups to share their last expression and their reasoning.
As each group shares, ask others in the class if they used the same strategy to write their expression and if they arrived at a similar expression.

Activity 2

Standards Alignment

Building On

Addressing

Building Toward

Instructional Routines

Number Talk

Materials

None

Activity Narrative

The purpose of this activity is for students to reason about addition and apply their reasoning to complete a partially-completed Number Talk routine. This time, students are given addition expressions and are asked to think about how the values of the sums could be found mentally. They then write two new addition expressions to complete the set.

Action and Expression: Internalize Executive Functions. To support working memory, provide students with access to sticky notes or mini whiteboards.
Supports accessibility for: Memory, Organization

Launch

Groups of 2–4
“Here are two expressions like the kinds you might see in a Number Talk.”

Activity

“How would you find the value of each expression, without writing? For each expression, think of at least two ways. Then share your thinking with your group.”
Reiterate to students that they are to consider how someone might reason about each sum, rather than only find the value.
3 minutes: independent work time
3 minutes: small-group discussion
“Write two more expressions that could go with the other two expressions to complete a Number Talk routine.”
5 minutes: small-group work time
Monitor for groups who consider the following strategies in writing their expression:
- Adjust the 504 to a different number, but keep the 199.
- Leave the 504, but adjust the 199.
- Adjust the 504 and the 199, but create a problem that can be reasoned as in previous expressions.
Identify groups, who chose different strategies, to share in the Activity Synthesis.

Here are 2 addition expressions.

Think of at least 2 different strategies you can use to find the value of each sum mentally.
Write 2 more addition expressions whose value can be found using the strategies you thought of.

Student Response

to access Student Response.

Advancing Student Thinking

Activity Synthesis

Select groups to share their two expressions and their reasoning.
As each group shares, ask others in the class if they used the same strategy to write their expressions and if they arrived at similar expressions.

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Lesson 15

Number Talk

Warm-up

Instructional Routines

Materials

Activity Narrative

Launch

Activity

Student Response

Advancing Student Thinking

Activity Synthesis

Activity 1

Standards Alignment

Building On

Addressing

3.NBT.A.2

Building Toward

Instructional Routines

Materials

Activity Narrative

Launch

Activity

Activity Synthesis

Activity 2

Standards Alignment

Building On

Addressing

3.NBT.A.2

Building Toward

Instructional Routines

Materials

Activity Narrative

Launch

Activity

Student Response

Advancing Student Thinking

Activity Synthesis

Activity 3

Standards Alignment

Building On

Addressing

3.NBT.A.2

Building Toward

Instructional Routines

Materials

Activity Narrative

Launch

Activity

Student Response

Advancing Student Thinking

Activity Synthesis

Activity 4

Standards Alignment

Building On

3.NBT.A.2

Addressing

Building Toward

Instructional Routines

Materials

Activity Narrative

Launch

Activity

Student Response

Advancing Student Thinking

Activity Synthesis

Lesson Synthesis

Standards Alignment

Building On

Addressing

3.NBT.A.2

Building Toward

Student Response

Advancing Student Thinking