• Unit Overview

  • Letter Home
  • Unit Preparation
  • Mathematics in this Unit
  • Assessment in this Unit
  • Key Assessment Opportunities Chart
• Daily Practice and Problems
• Home Practice

• Lesson 1

  • Part 1: Number Sentences for Tile Designs
  • Part 2: Use Symbols to Compare Number Sentences
  • Part 3: Create Individual Tile Designs
  • Summarizing the Lesson
  • Homework and Practice
  • Extension
  • Answer Keys

• Lesson 2

  • Developing the Lesson
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 3

  • Part 1: Solving Word Problems
  • Part 2: Writing Word Problems
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 4

  • Developing the Lesson
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 5

  • Part 1: Patterns on the 200 Chart
  • Part 2: Building 100 and 200
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 6

  • Part 1: Moving on the 200 Chart
  • Part 2: Addition and Subtraction on the 200 Chart
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 7

  • Part 1: Compare the 200 Chart and the Number Line
  • Part 2: Moving on the Number Line Game
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 8

  • Part 1: Many Ways to Solve a Problem
  • Part 2: Solving Problems Two Ways to Check for Reasonableness
  • Summarizing the Lesson
  • Homework and Practice
  • Answer Keys

• Lesson 9

  • Developing the Lesson
  • Summarizing the Lesson
  • Homework and Practice
  • Extension
  • Answer Keys

Lesson 3

Explore Subtraction Word Problems

Est. Class Sessions: 2

Daily Practice and Problems

X

Teacher Notes

X

Write 13 + 7 = 20 on the board and use two ten frames to model this number sentence. Have students explain their thinking. Have connecting cubes readily available.

1. A. less than 20
   
   B. more than 20
   
   C. less than 20
   
   D. less than 20
2. A possible strategy: It will take 7 more to add with 13 to make 20. 8 is one more than 7, so 13 + 8 is more than 20.

3. A. 18                 B. 21
   
   C. 18                 D. 18

4. Possible response: I know 4 + 4 = 8 and 8 + 10 = 18 so 4 + 14 = 18.

J. More Than or Less Than 20

1. Without solving the problem, decide if the sum is more or less than 20.

1. 12 + 6 _________
2. 13 + 8 _________
3. 13 + 5 _________
4. 4 + 14 _________

2. Show or tell your thinking for Question B.





3. What is the sum of each problem?

1. 12 + 6 _________
2. 13 + 8 _________
3. 13 + 5 _________
4. 4 + 14 _________

4. Show or tell how to solve 4 + 14.