# 4 Subtraction Concepts

Like addition, subtraction concepts are built on number recognition and counting principles. Learners need to develop the understanding that numbers can be decomposed into smaller numbers. Learners should understand that whole numbers can be separated into two or more number parts. This again, is the principle of part-part-whole.

##### EXPLORING SUBTRACTION
1. Have learners begin with a number and use the counting back skill to count another number.
2. Ask learners for the result.
3. Have learners reset the Nudget and begin with a different number.
4. Have learners count backward to find the other part of the number.
5. Have learners write down the starting number (whole) and the number counted back (part) and the result (part).

Start with the number 5.

Count back 3 checkers.

Learners write:  5 3 = 2

Provide learners opportunity to explore decomposing numbers to find the parts until the concept is learned. Having learners write down each number assists with visual learning and with connecting to abstract notation.

##### BASIC SUBTRACTION FACTS
1. Ask learners how many ways they can break apart the number 3.

Start from 3.

Count back 1 checker.

Write:   3 1 = 2

Start from 3.

Count back 2 checkers.

Write:   3 2 = 1

Start from 3.

Count back 3 checkers.

Write:   3 3 = 0

2.  Guide learners to understanding that 3 can be broken down into the following parts: 1 and 2, 2 and 1, 3 and 0, or 0 and 3.

3.  Explain these are the parts of the fact family of 3.

4.  Have learners write the fact family.

5.  Have learners find all the ways to separate or decompose other numbers like 4, 5, 6 etc.

6.  Have learners write the numbers in each fact family.

The fact family of the number 3:

Provide learners opportunity to master fact families through 10. It is important that fluency of basic facts is developed along with the concept of decomposing numbers. Facilitate learners in connecting the part-part-whole principle with composing and decomposing numbers.

## License

Number Nudget: Developing Number Concepts Copyright © by Kimberly Chappell. All Rights Reserved.