Curriculum  /  Math  /  2nd Grade  /  Unit 2: Adding and Subtracting Within 100  /  Lesson 3

Adding and Subtracting Within 100

Lesson 3

Math

Unit 2

2nd Grade

Lesson 3 of 21

Objective

Use make a ten strategies to add two-digit numbers within 50.

Student-Facing

I can use make a ten strategies to add two-digit numbers.

Common Core Standards

Core Standards

  • 2.NBT.B.5 — Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.

Foundational Standards

  • 1.NBT.C.4
  • 1.NBT.C.5
  • 1.NBT.C.6

Criteria for Success

  1. When adding, use addends to make a ten to add within 100. 
  2. Recognize patterns to multiples of ten when adding within 100. 

Tips for Teachers

  • In Grade 1, students focused on adding within 100 by adding a two-digit number to a one-digit number or a multiple of 10 (1.NBT.C.4). This lesson is designed for students to practice adding 2 two-digit numbers together within 50 by using make ten strategies. In Lesson 7, students will apply the same strategies within 100. 
  • To help students visualize making a ten, linking cubes are a great visual to model this. As students become more flexible in their thinking, they can show this by using number bonds.

Lesson Materials

  • Linking cubes (43 cubes total in at least two colors to show groups of 10 in alternating colors) — optional sets provided to students

Warm Up

5-10 minutes

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Anchor Tasks

15-25 minutes

Problem 1

Albert looks at the two stacks of linking cubes shown below.

Albert says he sees 20 + 23 when he looks at the cubes to add. Explain Albert’s thinking.

Purpose

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Set Up

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Problem 2

Make friendly numbers to add. 

a.   12 + 29 = _____

b.   25 + 17 = _____

c.   18 + 26 = _____

Purpose

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Problem 3

Fill in the missing numbers. Show your thinking by making friendly numbers.

a.   _____ = 17 + 29 

b.   27 + 13 = _____

c.   25 + 16 =_____

d.   _____ = 19 + 23

Purpose

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Problem Set

15-20 minutes

Target Task

5-10 minutes

Solve. Make a friendly number to solve. 

a.   _____= 13 + 29

b.   31 + 12 = _____

c.   _____= 39 + 11

d.   27 + 18 =_____

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

Use base ten blocks to represent adding within 100.

Lesson 4
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Lesson Map

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

Topic A: Adding & Subtracting with Multiples of Ten

Topic B: Strategies for Adding within 100

Topic C: Strategies for Subtracting within 100

Topic D: Working within 100 and Categorical Data

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