Borrowing from Our Neighbors: Mastering 3-Digit Subtraction with Regrouping

Mathematics Grades 4th Grade 3:20 Video
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Lesson Description

Learn how to subtract 3-digit numbers when you need to borrow (regroup) from the tens or hundreds place. This lesson breaks down the process step-by-step, making subtraction easy to understand!

Video Resource

Subtracting: three digit numbers and regrouping | Arithmetic | Khan Academy

Khan Academy

Duration: 3:20
Watch on YouTube

Key Concepts

  • Place Value (hundreds, tens, ones)
  • Regrouping (borrowing)
  • Subtraction of 3-digit numbers

Learning Objectives

  • Students will be able to identify when regrouping is necessary in 3-digit subtraction.
  • Students will be able to accurately regroup from the hundreds and tens place.
  • Students will be able to subtract 3-digit numbers with regrouping.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing basic subtraction facts. Ask students if they've ever had to 'borrow' something. Relate this to borrowing in math when subtracting.
  • Video Viewing (7 mins)
    Watch the Khan Academy video 'Subtracting: three digit numbers and regrouping'. Encourage students to pay attention to how the numbers are expanded and how regrouping works.
  • Guided Practice (15 mins)
    Work through example problems on the board, explaining each step of the regrouping process. Start with problems requiring regrouping only in the tens place, then move to problems requiring regrouping in both the tens and hundreds places. Use base-10 blocks as a visual aid to demonstrate regrouping.
  • Independent Practice (15 mins)
    Provide students with a worksheet containing 3-digit subtraction problems with varying levels of regrouping. Circulate to provide assistance and answer questions.
  • Wrap-up (3 mins)
    Review the key steps of regrouping and address any remaining questions. Preview the next lesson.

Interactive Exercises

  • Base-10 Block Subtraction
    Use base-10 blocks to physically represent the numbers in a subtraction problem. Students can then physically 'regroup' by trading a hundreds block for ten tens blocks, or a tens block for ten ones blocks. This provides a concrete understanding of the regrouping process.
  • Online Subtraction Game
    Play an online game that focuses on 3-digit subtraction with regrouping. This can provide a fun and engaging way for students to practice their skills.

Discussion Questions

  • Why is it important to understand place value when subtracting?
  • What does it mean to 'regroup' or 'borrow' in subtraction?
  • How can you check your answer to make sure your subtraction is correct?

Skills Developed

  • Subtraction skills
  • Problem-solving skills
  • Understanding of place value
  • Critical Thinking

Multiple Choice Questions

Question 1:

What does it mean to regroup in subtraction?

Correct Answer: To borrow from the next biggest place value

Question 2:

In the number 345, what is the value of the 4?

Correct Answer: 40

Question 3:

When do you need to regroup?

Correct Answer: When the bottom number is bigger than the top number

Question 4:

If you borrow 1 from the hundreds place, how many tens do you get?

Correct Answer: 10

Question 5:

What is 423 - 185?

Correct Answer: 238

Question 6:

What is the first step in subtracting 356 - 178?

Correct Answer: Subtract the ones place

Question 7:

In the problem 521 - 246, which place value needs to be regrouped first?

Correct Answer: Ones

Question 8:

What does it mean when you 'borrow' from the hundreds place?

Correct Answer: You are taking away 100

Question 9:

What is 600 - 234?

Correct Answer: 366

Question 10:

Why do we expand the numbers?

Correct Answer: To better visualize what we are regrouping

Fill in the Blank Questions

Question 1:

When you don't have enough to subtract, you need to _________.

Correct Answer: regroup

Question 2:

In the number 275, the 7 is in the _________ place.

Correct Answer: tens

Question 3:

When we regroup, we are actually changing the _________ of the number.

Correct Answer: place value

Question 4:

600 + 20 + 9 is the _________ form of 629.

Correct Answer: expanded

Question 5:

If you take 100 from 500, you have _________ left.

Correct Answer: 400

Question 6:

12 tens is the same as _________.

Correct Answer: 120

Question 7:

500 + 120 + 9 = _________.

Correct Answer: 629

Question 8:

When you borrow from the tens place, you add _________ to the ones place.

Correct Answer: 10

Question 9:

The Khan Academy video shows us how to subtract _________ numbers.

Correct Answer: 3-digit

Question 10:

When subtracting, always start with the _________ place.

Correct Answer: ones

Educational Standards

4.N.1.2:Use place value to describe whole numbers between 1,000 and 1,000,000 in terms of millions, hundred thousands, ten thousands, thousands, hundreds, tens, and ones with written, standard, and expanded forms. 4.N.2.4:Apply and analyze models to solve multi-step problems requiring the use of addition, subtraction, and multiplication of multi-digit whole numbers. Use various strategies, including the relationship between operations, the use of appropriate technology, and the context of the problem to assess the reasonableness of results.

Teaching Materials

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