Conquering Subtraction with Zeroes: Regrouping Like a Pro!

Mathematics Grades 4th Grade 2:24 Video
Print Lesson Plan Watch Video

Lesson Description

Learn how to subtract numbers when you have zeroes in the tens or hundreds place! This lesson will teach you how to regroup like a math superhero!

Video Resource

Subtracting: Regrouping from zero | Addition and subtraction | Arithmetic | Khan Academy

Khan Academy

Duration: 2:24
Watch on YouTube

Key Concepts

  • Place Value
  • Regrouping (Borrowing)
  • Subtraction Algorithm

Learning Objectives

  • Students will be able to identify when regrouping is necessary in subtraction problems with zeroes.
  • Students will be able to correctly regroup from the hundreds place to the tens and ones place when subtracting.
  • Students will be able to accurately subtract multi-digit numbers involving regrouping across zeroes.

Educator Instructions

  • Introduction (5 mins)
    Begin by reviewing basic subtraction and the concept of regrouping (borrowing) when the digit being subtracted is larger than the digit it's being subtracted from. Ask students for examples when they have to borrow. Briefly discuss what happens when there is a zero in the tens place.
  • Video Viewing (7 mins)
    Play the Khan Academy video: 'Subtracting: Regrouping from zero | Addition and subtraction | Arithmetic | Khan Academy'. Encourage students to follow along and pause the video at key points to discuss the steps being taken.
  • Guided Practice (10 mins)
    Work through 2-3 subtraction problems with zeroes in the tens place as a class. Emphasize the steps of regrouping from the hundreds place, then the tens place. Verbalize each step: 'We can't subtract 4 from 1, so we need to borrow from the tens place. But the tens place is a zero, so we need to borrow from the hundreds place first.' Ensure everyone understands the logic.
  • Independent Practice (10 mins)
    Give students 3-4 similar subtraction problems to solve independently. Circulate to provide support and address any confusion. Encourage students to check their answers by adding the difference to the subtrahend to see if they arrive at the minuend.
  • Review and Closure (3 mins)
    Review the key steps of regrouping across zeroes. Ask students to share any strategies or tips they found helpful. Reiterate the importance of place value in subtraction.

Interactive Exercises

  • Number Line Regrouping
    Use a number line to visualize regrouping. For example, when subtracting from 301, show how taking 100 from the 300 is like moving back 100 on the number line. Then, show how taking 10 from that 100 to add to the ones place works.
  • Base Ten Blocks
    Use base ten blocks to physically represent the regrouping process. Start with 3 hundreds and 1 one. Show how you need to exchange one hundred block for ten ten-blocks and then exchange one ten-block for ten one-blocks to be able to subtract.

Discussion Questions

  • Why is it important to understand place value when regrouping?
  • What do you do if you need to borrow from the tens place, but the tens place is a zero?
  • How can you check your answer to make sure you subtracted correctly?

Skills Developed

  • Problem-solving
  • Critical Thinking
  • Place Value Understanding
  • Subtraction Fluency

Multiple Choice Questions

Question 1:

What do you need to do FIRST if you have to subtract a bigger number from a smaller number?

Correct Answer: Regroup (borrow)

Question 2:

If the tens place is zero, where do you regroup from first?

Correct Answer: The hundreds place

Question 3:

What does the hundreds place become after you regroup?

Correct Answer: One number smaller

Question 4:

What does the tens place become after you regroup from the hundreds place?

Correct Answer: 10

Question 5:

After regrouping the tens place, what number do you regroup from in the tens place?

Correct Answer: 9

Question 6:

In the problem 402 - 156, what is the first step?

Correct Answer: Regroup from the hundreds place

Question 7:

When regrouping from the hundreds place, how many tens do you add to the tens place?

Correct Answer: 10

Question 8:

Which problem needs regrouping from zero?

Correct Answer: 301 - 125

Question 9:

After regrouping the tens place, how many ones do you add to the ones place?

Correct Answer: 10

Question 10:

What is the value of the tens place after you borrow to give to the ones column, after having a value of 10?

Correct Answer: 9

Fill in the Blank Questions

Question 1:

When subtracting, if the top number is smaller than the bottom number, you need to ___________.

Correct Answer: regroup

Question 2:

If the tens place has a ___________, you can't borrow from it right away.

Correct Answer: zero

Question 3:

When the tens place is zero, you need to borrow from the ___________ place first.

Correct Answer: hundreds

Question 4:

When you borrow from the hundreds place, you give ___________ to the tens place.

Correct Answer: 10

Question 5:

After borrowing from the hundreds place, the hundreds place becomes one number ___________.

Correct Answer: smaller

Question 6:

After borrowing from the tens place, you give ___________ to the ones place.

Correct Answer: 10

Question 7:

After borrowing from the hundreds place, the tens place has a value of ___________.

Correct Answer: 10

Question 8:

After giving value to the ones place, the tens place has a value of ___________.

Correct Answer: 9

Question 9:

400 - 100 = ___________.

Correct Answer: 300

Question 10:

To make sure that you subtracted correctly, you can check by __________.

Correct Answer: adding

Educational Standards

4.N.1:[Standard] Compare and represent whole numbers up to 1,000,000 with an emphasis on place value and equality. 4.N.2:[Standard] Solve real-world and mathematical problems using multiplication and division. 4.N.2.4:[Objective] 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

Download ready-to-use materials for this lesson:

Student Worksheet Classroom Slides Assessment Quiz
Add to Google Classroom

User Actions

Sign in to save this lesson plan to your favorites.

Sign In

Share This Lesson

Related Lesson Plans