Curriculum  /  Math  /  2nd Grade  /  Unit 5: Adding and Subtracting Within 1,000  /  Lesson 23

Adding and Subtracting Within 1,000

Lesson 23

Math

Unit 5

2nd Grade

Lesson 23 of 25

Objective

Solve addition computations within 1,000 and explain strategies.

Student-Facing

I can solve addition computations within 1,000 and explain my strategy.

Common Core Standards

Core Standards

  • 2.NBT.B.6 — Add up to four two-digit numbers using strategies based on place value and properties of operations.
  • 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.
  • 2.NBT.B.9 — Explain why addition and subtraction strategies work, using place value and the properties of operations. Explanations may be supported by drawings or objects.

Foundational Standards

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

Criteria for Success

  1. Solve four two-digit addend equations using various methods and explain thinking. 
  2. Solve addition computations within 1,000 and explain strategies used to solve.

Tips for Teachers

  • Students got exposure to solve 4 two-digit addend problems in Unit 2 within 100 but in this lesson they will revisit with sums that are within 1,000. Students will be able to use their various addition skills in context to add efficiently. 
  • In the problem set, in problems with 4 two-digit addends, students may not always see explicit pairs to 10 or 100 but can still make sense of the numbers by combining as they see fit. 

Warm Up

5-10 minutes

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Anchor Tasks

15-25 minutes

Problem 1

a.   Sherri said that she likes to make pairs to 10 and 100 when she's adding and used that thinking to solve the following:

73 +20 + 34 + 57 = _____

b.   Solve and show how you solved. 

  1. 50 + 45 + 69 + 51 =_____
  2. 80 + 16 + 54 + 27 = _____

Purpose

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Problem 2

Use a strategy and show how you solve. 

a.   _____ = 250 + 505 

b.   435 + 87 = _____

c.   324 + 298 = _____

d.   _____ - 98 = 283

Purpose

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Problem Set

15-20 minutes

Target Task

5-10 minutes

Solve and explain your thinking.

a.   68 + 436 = _____

b.   48 + 35 + 64 + 30 = _____

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

Solve subtraction computations within 1,000 and explain strategies.

Lesson 24
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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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