options: Apply and extend previous understandings of addition and subtraction to add and subtract rational numbers; represent addition and subtraction on a horizontal or vertical number line diagram.

Solve real-world and mathematical problems involving the four operations with rational numbers. (Computations with rational numbers extend the rules for manipulating fractions to complex fractions.)

Apply and extend previous understandings of multiplication and division and of fractions to multiply and divide rational numbers.
problem_activity: Warm-up
The purpose of this activity is to remind students of a few details to keep in mind when doing arithmetic with signed numbers, particularly that subtracting a number has the same result as adding its opposite, and the sign of the product when multiplying two negative numbers, or a positive by a negative number.
Student Facing
Sort these into two groups, so that the expressions in each group all have the same value.
\(3-5\)
\(5+3\)
\(4 \boldcdot 2\)
\(\text- \frac13 \boldcdot 6\)
\(5 - \text-3\)
\(\text-4 \boldcdot \text-2\)
\(3 + \text-5\)
\(\frac13 \boldcdot \text-6\)
Student Response
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Activity Synthesis
Use students’ explanations for why expressions are equal to draw attention to things to keep in mind when doing arithmetic on signed numbers. For example:
Subtracting a number has the same result as adding its opposite.
\(3-5=3+\text-5\)
Multiplying a negative number by a negative number results in a positive product.
\(\text-4  \boldcdot \text-2\)
and
\(4 \boldcdot 2\)
are both equal to 8.
Multiplying a negative number by a positive number results in a negative product
\(\text- \frac13 \boldcdot 6\)
and
\(\frac13  \boldcdot \text-6\)
are both equal to -2.


correct_option_index: 0

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