Borrowing Buddies: Mastering 3-Digit Subtraction with Regrouping!

Mathematics Grades 4th Grade 2:47 Video
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Lesson Description

Learn how to subtract 3-digit numbers using regrouping! This lesson breaks down the 'borrowing' process to make subtraction simple and fun.

Video Resource

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

Khan Academy

Duration: 2:47
Watch on YouTube

Key Concepts

  • Place Value (Hundreds, Tens, Ones)
  • Regrouping (Borrowing)
  • Subtraction Algorithm

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 tens and hundreds place to subtract 3-digit numbers.
  • Students will be able to solve 3-digit subtraction problems with regrouping using the standard algorithm.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing basic subtraction and place value (hundreds, tens, ones). Ask students to solve a simple 2-digit subtraction problem without regrouping. Then, present a 3-digit subtraction problem that requires regrouping (e.g., 321 - 119). Ask students what makes this problem different and introduce the concept of 'borrowing' or 'regrouping'.
  • Video Viewing (7 mins)
    Play the Khan Academy video "Subtracting: three digit numbers and basic regrouping." Encourage students to pay close attention to how the presenter explains the concept of regrouping and how it relates to place value.
  • Expanded Form Explanation (8 mins)
    After the video, reinforce the concept by writing a subtraction problem in expanded form as demonstrated in the video (e.g., 971 = 900 + 70 + 1). Work through the problem, showing how to 'borrow' a ten from the tens place and add it to the ones place. Emphasize that the value of the number doesn't change, only the representation.
  • Standard Algorithm Practice (10 mins)
    Transition to practicing the standard subtraction algorithm with regrouping. Work through several example problems on the board, explaining each step clearly. Have students follow along in their notebooks. Emphasize aligning digits correctly according to place value.
  • Independent Practice (10 mins)
    Provide students with a worksheet containing 3-digit subtraction problems that require regrouping. Circulate the classroom to provide assistance and answer questions.

Interactive Exercises

  • Place Value Regrouping Game
    Use base-ten blocks or drawings to represent 3-digit numbers. Have students physically regroup (exchange) a ten-rod for ten unit cubes or a hundred-flat for ten ten-rods to solve subtraction problems.
  • Online Regrouping Practice
    Utilize online resources like Khan Academy or other educational websites that offer interactive practice problems with immediate feedback on 3-digit subtraction with regrouping.

Discussion Questions

  • When do you need to regroup when subtracting?
  • How does understanding place value help you with regrouping?
  • Can you explain in your own words how to regroup from the tens place to the ones place?
  • What happens if you can't regroup from the tens place? (Hint: Look at the hundreds place!)

Skills Developed

  • Problem-solving
  • Critical Thinking
  • Place Value Understanding
  • Procedural Fluency (Subtraction Algorithm)

Multiple Choice Questions

Question 1:

What is 'regrouping' in subtraction?

Correct Answer: Borrowing from another place value

Question 2:

In the number 452, what does the 5 represent?

Correct Answer: 5 tens

Question 3:

If you need to subtract 7 from 3, what do you need to do?

Correct Answer: Switch the numbers

Question 4:

What is 523 - 218?

Correct Answer: 305

Question 5:

What place value do you regroup from first when subtracting 651 - 289?

Correct Answer: Tens

Question 6:

When you regroup 1 ten, how many ones do you get?

Correct Answer: 10

Question 7:

Solve: 714 - 356

Correct Answer: 358

Question 8:

In the problem 825 - 462, do you need to regroup?

Correct Answer: Yes, from the tens place

Question 9:

What is 900 - 543?

Correct Answer: 357

Question 10:

Why is it important to line up numbers by place value when subtracting?

Correct Answer: Both B and C

Fill in the Blank Questions

Question 1:

When you regroup, you are _________ from another place value.

Correct Answer: borrowing

Question 2:

In the number 678, the 6 is in the _________ place.

Correct Answer: hundreds

Question 3:

If you regroup 1 hundred, you get _________ tens.

Correct Answer: 10

Question 4:

To solve 425 - 117, you must first regroup from the _________ place.

Correct Answer: tens

Question 5:

When you regroup, you are changing the _________ of the digits, but not the value of the number.

Correct Answer: place

Question 6:

852 - 329 = _________

Correct Answer: 523

Question 7:

The number 100 can be shown as 10 _________.

Correct Answer: tens

Question 8:

When the top number in a column is smaller than the bottom number, you need to _________.

Correct Answer: regroup

Question 9:

700 - 250 = _________

Correct Answer: 450

Question 10:

The first step in subtracting 3-digit numbers is lining up the numbers by their _________.

Correct Answer: place value

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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