Subtraction does not work with the commutative property ... or does it? Confronted with a difficult problem, the narrator realizes that by writing the subtractions as adding a negative, he can rearrange the problem. Pupils learn that as long as they use addition to represent subtraction, they can reorder the problem to make the computations easier.

Concepts

subtraction, subtraction integers, commutative property of addition, commutative property, subtraction whole numbers, addition integers, integers

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Additional Tags

math

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Instructional Ideas

• Provide opportunities for the class to practice several similar problems

Classroom Considerations

• Individuals should know how to add and subtract integers
• Expects students understand the distribution of a negative sign

Pros

• Uses a word problem as an example of the concept
• Shows all of the intermediate steps in solving the problem

Cons

• None

Common Core

SL.7.2 7.NS.A.1.a 7.NS.A.1.c 7.NS.A.1.d MP1 MP6 MP7