WEBVTT
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Which of the following describes the given model?
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Before we choose one of the equations, let’s think about what this model represents.
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We have a rectangle.
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How many pieces is this rectangle divided into?
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One, two, three, four, five, six, seven, eight.
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This whole is divided into eight parts.
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One thing that we can do is look at our answer choices and remove any of them that aren’t divided into eight parts.
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Answer choice a says five-ninths plus three-ninths equals eight-ninths, but we’re not talking about ninths.
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So we can remove answer choice a.
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For the same reason, we can also remove answer choice d.
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Okay, back to our model.
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In our model, pieces three four and five have an X through them.
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That X represents taking away.
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We represent take away mathematically by using subtraction.
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So we can eliminate answer choice c because it is an addition problem.
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We know that we’re dealing with subtraction.
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But in order to find the correct problem, we need to know what fraction did we start with.
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Originally five out of the eight were shaded.
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Five-eighths were blue.
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Three-eighths were crossed out.
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And we use subtraction.
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So we say five-eighths minus three-eighths.
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And there were two-eighths blue-shaded pieces remaining.
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I notice that the answer choice e starts with four- eighths and not five-eighths.
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And that leaves us with answer choice b: five-eighths minus three-eighths equals one-fourth.
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But wait!
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Two out of the eight were still shaded.
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Why does the answer choice say one-fourth?
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Two-eighths and one-fourth are equivalent fractions.
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If you divide two by two, you get one in the numerator.
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And if you divide eight by two, you get four.
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Remember, when we’re working with fractions, we can divide the numerator and the denominator by the same number and we haven’t changed the value of that fraction.
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They are equivalent fractions.
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Five-eighths minus three-eighths equals one-fourth can be described with the given model.