Lesson 17 | Adding and Subtracting Within 100 | 2nd Grade Mathematics

Objective

Use place value strategies to add 4 two-digit numbers within 100.

Student-Facing

I can use place value knowledge to add 4 two-digit numbers within 100.

Common Core Standards

Core Standards

The core standards covered in this lesson

2.NBT.B.6 — Add up to four two-digit numbers using strategies based on place value and properties of operations.

Number and Operations in Base Ten

2.NBT.B.6 — Add up to four two-digit numbers using strategies based on place value and properties of operations.

Foundational Standards

The foundational standards covered in this lesson

1.NBT.B.2

Number and Operations in Base Ten

1.NBT.B.2 — Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
1.NBT.C.4

Number and Operations in Base Ten

1.NBT.C.4 — Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, 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 and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.
1.OA.C.6

Operations and Algebraic Thinking

1.OA.C.6 — Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 - 4 = 13 - 3 - 1 = 10 - 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 - 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).

Criteria for Success

The essential concepts students need to demonstrate or understand to achieve the lesson objective

Use place value knowledge to add 4 two-digit addends.
Decompose addends into tens and ones as a strategy to add.

Warm Up

5-10 minutes

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Anchor Tasks

Tasks designed to teach criteria for success of the lesson, and guidance to help draw out student understanding

15-25 minutes

Problem 1

Rena says that adding using place value thinking helps her add 4 two-digit numbers easily. She started to solve below.

30 + 17 + 41 + 11 =

30 + 10 + 40 + 10 = 90

a. Finish solving the problem using Rena’s thinking.

b. Explain Rena’s strategy.

Purpose

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Problem 2

Use place value thinking to solve the following problems.

a. 43 + 21 + 15 + 20 =

b. 29 + 31 + 11 + 25 =

Purpose

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Problem 3

Mr. Han's class kept track of the number of sunny days in the first four months of the year.

Month	Number of sunny days
January	22
February	18
March	24
April	21

How many total sunny days were there in January through April? Show your thinking.

Purpose

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Problem Set

15-20 minutes

Target Task

A task that represents the peak thinking of the lesson - mastery will indicate whether or not objective was achieved

5-10 minutes

Makayla solved the following problem and got 80. Solve and show your thinking to see if you get the same total.

14+ 27 + 26 + 23 =

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.

Adding and Subtracting Within 100

Objective

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Student-Facing

Common Core Standards

Core Standards

Number and Operations in Base Ten

Foundational Standards

Number and Operations in Base Ten

Number and Operations in Base Ten

Operations and Algebraic Thinking

Criteria for Success

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Warm Up

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Anchor Tasks

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Problem 1

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Purpose

Problem 2

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Purpose

Problem 3

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Purpose

Problem Set

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Target Task

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Student Response

Additional Practice

Word Problems and Fluency Activities

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