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Practice

How can we relate addition and subtraction?

Goal:

Goal:

thinking monkey with addition and subraction sign

Think About It!

Goal: How do addition and subtraction sentences use the same numbers?

We can use the numbers 2, 3, and 5 to create subtraction sentences, too. Let’s look at the hamsters at the pet store again.

3 tan hamsters and 2 brown hamsters.

There are 5 hamsters at the pet store. 3 of the hamsters are tan.

Question

How many hamsters are white and brown?

We know there are 2 white and brown hamsters because 5 - 3 = 2. This subtraction sentence has two parts and a whole. Just like the addition sentences, the tan hamsters make up one part and the white and brown hamsters make up the other part. All of the hamsters together make up the whole.

5   -   3   =   2

5 hamsters. 3 are tan, and 2 are brown.

Whole     -     Part     =     Part

Can you switch the parts to make another subtraction sentence that is related to 5 - 3 = 2?

Insert the subtraction sentence in the blank below. Check your answer by clicking the Check button.

- =

Yes! This is the correct subtraction sentence.

Sorry, that was the incorrect answer. Remember subtraction sentences are written in the form: whole - part = part.

Great job! We built two addition sentences and two subtraction sentences about the hamsters. All of these number sentences are related because they use the same numbers: 2, 3, and 5. 2 and 3 are the parts, and 5 is the whole. We can organize this information in a part-part-whole chart. A part-part-whole chart is a rectangle with three sections. Two of the sections are labeled “part,” and one of the sections is labeled “whole.” Look at the example below. To move to the next example, click the arrow on the right.

Part-part-whole-chart. 3 tan hamsters in one part, 2 brown hamsters in the other part, and 5 hamsters in the whole part.

3 + 2 = 5

2 + 3 = 5

This part-part-whole chart is used for addition. Addition sentences look like this: part + part = whole. Just like an addition sentence, the parts come first in this part-part-whole chart.

Part-part-whole-chart. 3 tan hamsters in one part, 2 brown hamsters in the other part, and 5 hamsters in the whole part

5 - 2 = 3

5 - 3 = 2

This part-part-whole chart is a little different than the one we just looked at. This chart is used for subtraction. Subtraction sentences look like this: whole - part = part. Just like a subtraction sentence, the whole comes first in this part-part-whole chart.

Let’s look at two more part-part-whole charts. There are 2 green birds and 6 blue birds in both of these charts. We can use the first chart to create 2 addition sentences. We will use the second chart to create 2 subtraction sentences. All 4 of these number sentences will be related because they use the same numbers: 2, 6, and 8. Can you fill in the missing whole to complete the related number sentences?

Part-part-whole-chart. 2 green birds in one part, 6 blue birds in the other part, and 8 birds in the whole part
Part-part-whole-chart. 8 birds in the whole part, 2 green birds in one part, and 6 blue birds in the other part.

Great job! You created 4 different number sentences using the same 3 numbers from the part-part-whole charts.