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Math / Integers / Grade 7 / mi7c2

Signed Changes: Explain a New Model

Use a starting position and a signed change to explain each result.

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Adding a positive number moves right; adding a negative number moves left. To subtract a number, add its opposite. Count intervals, not the starting tick. Check an answer by reversing the change.

Worked example

-2 - (-5) = -2 + 5 = 3. Start at -2, move five units right, and finish at 3. Check: 3 + (-5) = -2.

A number line with equal intervals from -8 to 8. An arrow starts at -2 and ends at 3: subtracting -5 means adding positive 5.
Worked model: subtract a number by adding its opposite.
Question 1 A model lift starts at level -6 and rises 4 levels. Where does it end?
Question 2 Calculate 5 + (-9).
Question 3 Calculate 1 - 6.
Question 4 Which expression equals 2 - (-5)?
Question 5 A position changes from -4 to 3. What signed change takes it there?