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5.04 Add and subtract fractions with models

Lesson

Are you ready?

Let's review how to identify a fraction using a model. 

What fraction of the square is shaded blue?

Leave the answer in unsimplified form.

 

Learn

This video shows how to add and subtract fractions using an area model. 

Apply

question 1

In the image below, $\frac{6}{8}$68 has been shaded red and $\frac{1}{8}$18 has been shaded blue.

  1. Write the addition that describes the image.

  2. What is the total shaded?

 

question 2

The image below shows $\frac{8}{10}$810 of the rectangle shaded.
 

  1. We now want to take away $\frac{1}{10}$110.

    What is the answer to $\frac{8}{10}-\frac{1}{10}$810110?

 

Remember!

Area models can help us see the parts of fractions that are being added or subtracted. 

 

Outcomes

4.NF.3

Understand a fraction a/b with a > 1 as a sum of fractions 1/b. In other words, any fraction is a sum of unit fractions.

4.NF.3.b

Decompose a fraction into a sum of fractions with the same denominator in more than one way, recording each decomposition by an equation. Justify decompositions, for example By using a visual fraction model.

4.NF.3.d

Solve word problems involving addition and subtraction of fractions referring to the same whole and having like denominators.

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