# Decompose to Subtract

Videos to help Grade 2 students learn how to decompose to subtract from a ten when subtracting within 20 and apply to one-step word problems.

Common Core Standards: 2.OA.1, 2.OA.2

Related Topics:
Common Core Math Resources, Lesson Plans & Worksheets for all grades

Common Core Math Video Lessons, Math Worksheets and Games for Grade

Common Core Math Video Lessons, Math Worksheets and Games for all grade

## New York State Common Core Math Module 1, Grade 2, Lesson 5

### NYS Math Module 1 Grade 2 Lesson 5

Using number bonds to decompose the ten and subtract from the tens. This is a mental math strategy that builds number sense and prepares students for problems with larger numbers.

Lesson 5 Concept Development

The focus of this activity is on solving problems with a common subtrahend (e.g., 11 – 8, 12 – 8, 13 – 8, etc.).
Next, students determine whether to subtract from the ten or the ones.

Lesson 5 Problem Set

1. Do we subtract from the tens or ones?
11 - 2 =
15 - 2 =
16 - 4 =

2. Fill in the blank to make the number sentence correct.
11 – 8 = 2 + ___
16 – 9 = 1 + ___

Lesson 5 Concept Development

Explain how to decompose to subtract within 20

Lesson 5 Homework

3. Mrs. Jones bought 12 eggs from the store in the morning. Her husband brought home 5 more eggs in the evening. They used 8 of the eggs for dinner. How many eggs do they have left?

4. 11 pink roses and 7 red roses grew in Mrs. Thompson’s garden. She gave away 9 of the pink roses to her neighbor. How many roses does she have left?
EngageNY/Eureka Math Grade 2 Module 1 Lesson 5 Version 3
Make a ten to add within 100
1. Solve
3. Use the RDW process to solve.
There were 28 students at recess. A group of 7 students came outside to join them. How many students are there now?