7.03 Add and subtract fractions with models
Are you ready?
Let's review how to identify a fraction using a model.
What fraction of the square is shaded blue?
You do not need to simplify the answer.
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This video shows how to add fractions using an area model.
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question 1
In the image below, $\frac{1}{2}$12 has been shaded red and $\frac{3}{8}$38 has been shaded blue.
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Write the addition that describes the image.
What is the total shaded?
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This video shows how to subtract fractions using an area model.
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question 2
The image below shows $\frac{2}{3}$23 of the rectangle shaded.
What is the equivalent fraction in sixths? $\frac{2}{3}=\frac{\editable{}}{6}$23=6
We now want to take away $\frac{3}{6}$36.
What is the answer to $\frac{2}{3}-\frac{3}{6}$23−36?
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We can also use number lines to add and subtract.
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question 3
We want to calculate the sum $\frac{1}{2}+\frac{3}{8}$12+38.
Complete the statement to make an equivalent fraction for $\frac{1}{2}$12.
$\frac{1}{2}=\frac{\editable{}}{8}$12=8
Plot $\frac{4}{8}$48 on the number line.
Choose the image below that represents the addition $\frac{1}{2}+\frac{3}{8}$12+38.
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Think about how the denominators are related.
We can use area models to change fractions to their equivalent fraction so the denominators are the same.