Curriculum  /  Math  /  2nd Grade  /  Unit 5: Adding and Subtracting Within 1,000  /  Lesson 19

Adding and Subtracting Within 1,000

Lesson 19

Math

Unit 5

2nd Grade

Lesson 19 of 25

Objective

Use expanded form to subtract within 1,000.

Student-Facing

I can use expanded form to subtract. 

Common Core Standards

Core Standards

  • 2.NBT.B.7 — Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.

Foundational Standards

  • 1.NBT.B.2
  • 2.NBT.A.1
  • 2.NBT.A.2

Criteria for Success

  1. Represent three-digit minuends and subtrahends in expanded form notation to subtract. 
  2. Subtract by place value.
  3. In situations where there are not enough tens and ones in the minuend to subtract, rewrite the minuend as a sum of more than 10 tens and ones, as necessary. 

Tips for Teachers

If students need the visual support, place value drawings or base ten blocks are tools that can support students as they engage with more abstract forms of subtraction with decompositions of larger units into more than 10 smaller units. This is explored in Anchor Task 1 but can be used in Anchor Task 2 to further support student thinking.

Lesson Materials

  • Optional: Base ten blocks
  • Optional: Hundreds place value chart (1 per student) — These should be laminated or in sheet protectors to reuse
  • Optional: Sheet protectors (1 per student)
  • Optional: Dry erase marker (1 per student)

Warm Up

5-10 minutes

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Anchor Tasks

15-25 minutes

Problem 1

Gena represented finding the difference  of 372 - 156 with a drawing and using an expanded form algorithm below.

Drawing :

Expanded Form: 

$$ \begin{array}{crcrcrcc} &300 &+ &70 &+ &2 &&&\\ - \ \ \ &100 &+ &50 &+ &6 &&&\\ \hline \end{array}$$

 

a.   Finish Gena's work using each method to find the difference.

b.   What was similar and different about the two methods?

Purpose

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Problem 2

Solve using expanded form. Rewrite the total as needed to subtract. 

a.   615 - 337 = _____

b.   450 - 66 = _____

c.   244 - 168 =_____

d.   200 - 86 = _____

Purpose

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Problem Set

15-20 minutes

Target Task

5-10 minutes

Solve using expanded form. Rewrite the total as needed to subtract. 

a.   725 - 549 = _____

b.   947 - 698 = _____

Student Response

Additional Practice

Daily Word Problems, Warm Ups, and Center Activities are aligned to the content of the unit but not necessarily to the lesson objective, therefore feel free to use them anytime during your school day.

Word Problems and Fluency Activities

Next

Relate subtraction with expanded form to the standard algorithm in situations with up to two decompositions of a ten or hundred.

Lesson 20
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Lesson Map

A7CB09C2-D12F-4F55-80DB-37298FF0A765

Topic A: Adding with Mental Strategies

Topic B: Adding within 1,000

Topic C: Subtracting with Mental Strategies

Topic D: Subtracting within 1,000

Topic E: Story Problems and Explaining Addition and Subtracting Thinking

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