Grade 5

Write the following story on the board and ask students to be prepared to justify all their responses.

A > B and C > D. Compare the following:

A + C __ B + D

A + D __ B + C

A – D __ B – C

What else could you say?

- A + C must be greater than B + D, because the sum of two larger numbers is greater than the sum of two smaller numbers.
- A + D can be equal to, greater than, or less than B + C, because it depends on what numbers you use for A, B, C, and D.
- A – D is greater than B – C, because A – D is subtracting a smaller number from a larger number, and B – C is subtracting a larger number from a smaller one.
- Both A – D and B – C could be less than 0.
- You can’t tell whether A – C or B – D is larger.

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