Unit 7, Lesson 4
Add and Subtract 3-Digit Numbers in Different Ways
Grade 2
Activity 1
Mai and Lin find the value of .
Mai’s work
Number line. No tick marks. Arrow from point at 387 to point at 487, labeled 100. Arrow from point at 487 to point at 497, labeled 10. Arrow from point at 497 to point at 500, labeled 3.
Lin’s work
Find the value of each expression.
Show your thinking, using drawings, numbers, or words.
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Try Mai’s way. Find the value of .
- Try Lin’s way. Find the value of .
Activity 2
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Andre and Diego show their thinking with equations. They find the value of .
Andre’s work
Diego’s work
How are Andre’s and Diego’s work alike? How are they different?
Show your thinking, using drawings, numbers, or words.
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Try Andre’s way. Find the value of .
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Try Diego’s way. Find the value of .
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Choose your own way to find the value of . Show your thinking, using drawings, numbers, or words.
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Choose your own way to find the value of . Show your thinking, using drawings, numbers, or words.
Student Section Summary
We compared 3-digit numbers. We used addition to find the difference. We added and subtracted by counting on or counting back. We wrote numbers in expanded form to add or subtract, using place value.