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Unit 3 - Lesson 11 - Grade 3: Illustrative Mathematics

Last updated 9 months ago
11 questions
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Grade 3 Unit 3
Lesson 11: Analyze Subtraction Algorithms
CC BY 2021 Illustrative Mathematics®
Grade 3 Unit 3
Lesson 11: Analyze Subtraction Algorithms
CC BY 2021 Illustrative Mathematics®
Lesson: Analyze Subtraction Algorithms

Number Talk: Subtract within 1,000 (Warm Up)

Find the value of each expression mentally.
1

400 - 200

1

450 - 200

1

450 - 205

1

450 - 215

Compare Two Subtraction Algorithms

The first steps of two algorithms are shown.

1

How are the steps different?

1

Use Algorithm A to find the value of 824 - 541.

1

Use Algorithm B to find the value of 824 - 541.

Use an Algorithm?

Noah wanted to find the value of 301 - 167 and wrote:


Elena said that we can’t subtract this way because we would need more ones to subtract 7 ones, but there’s a zero in the tens place of 301.
1

Do you agree with Elena's statement? Explain your reasoning.

1

Show how you would use an algorithm (either Noah's or another algorithm) to find the difference between 301 and 167.

Cool Down: Subtraction Reflection
You’ve learned many ways to subtract large numbers, including strategies and algorithms.
1

What is your favorite way to subtract large numbers?

1

What’s a way that you would like to learn more about and use more?