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Rally with Rounding

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k.j.horstmann

Tier 2
For Schools

Lesson Plan

Rally with Rounding

Students will be able to round multi-digit numbers to any place value using a vertical number line.

Rounding helps us estimate quickly in everyday life, like when we're shopping or trying to figure out how long something will take. It's a key skill for checking if our answers make sense in math problems!

Audience

4th Grade Students

Time

30 minutes

Approach

Through direct instruction, guided practice, and independent work using vertical number lines.

Materials

Whiteboard or Projector, Rounding Slide Deck, Dry-erase markers or pencils, Rounding Practice Worksheet, and Rounding Practice Answer Key

Prep

Teacher Preparation

10 minutes

  • Review the Rounding Slide Deck and familiarize yourself with the content.
  • Print or prepare to project the Rounding Practice Worksheet.
  • Have Rounding Practice Answer Key available for quick checking.
  • Ensure whiteboard or projector is ready for use.
  • Gather dry-erase markers or pencils for students.

Step 1

Warm-Up: What's Your Nearest Ten?

5 minutes

  • Teacher: Begin by asking students: "Imagine you're telling a friend how many jellybeans are in a jar. You don't know the exact number, but you want to give a quick, close guess. What would you do?" (Allow brief student responses, guiding them towards the idea of 'about' or 'around').
  • Teacher: "Today, we're going to learn a super helpful math skill called rounding, which is like making a smart guess! Let's try a quick warm-up. If I have 23 apples, about how many is that to the nearest ten?" (Guide students to 20). "What about 28 apples?" (Guide students to 30).
  • Teacher: "We'll explore how to do this for bigger numbers using a cool tool!"

Step 2

Introduction to Rounding & Vertical Number Lines

10 minutes

  • Teacher: Introduce the concept of rounding using the Rounding Slide Deck (Slides 1-3).
  • Teacher: "We're going to learn how to round big numbers using something called a vertical number line. It makes it really easy to see which number we're closer to!"
  • Teacher: Guide students through examples on the Rounding Slide Deck (Slides 4-7) demonstrating how to use a vertical number line to round to the nearest ten, hundred, and thousand. Emphasize identifying the rounding place, the digit to its right, and the 'midpoint' on the number line.
  • Teacher: "Remember, if the digit to the right is 5 or more, we round up! If it's less than 5, we round down!"

Step 3

Guided Practice

8 minutes

  • Teacher: Work through 2-3 additional examples as a class, using the whiteboard or projector to draw vertical number lines as shown in the Rounding Slide Deck.
  • Teacher: Provide students with a few practice problems to solve independently or with a partner on their own paper/whiteboards, circulating to offer support and check understanding.
    • Example 1: Round 4,729 to the nearest hundred.
    • Example 2: Round 12,351 to the nearest thousand.
  • Teacher: "Great job! Let's see how you did. Who can share their answer and explain how they used the vertical number line?" (Call on students to share their reasoning).

Step 4

Independent Practice: Worksheet Time!

5 minutes

  • Teacher: "Now it's your turn to 'Rally with Rounding' on your own! You will complete the Rounding Practice Worksheet. You can use vertical number lines to help you, just like we practiced."
  • Teacher: Distribute the Rounding Practice Worksheet and instruct students to complete the first few problems independently.
  • Teacher: Circulate around the room to monitor student progress and provide individual support as needed. Collect worksheets upon completion for review or check them together using the Rounding Practice Answer Key.

Step 5

Cool-Down: Quick Check

2 minutes

  • Teacher: "Before we wrap up, let's do one quick check. On a piece of paper or your whiteboard, round the number 3,487 to the nearest hundred."
  • Teacher: Collect responses or have students show their whiteboards. This serves as a quick assessment of understanding.
  • Teacher: "Excellent work today, everyone! You're becoming rounding masters!"
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Slide Deck

Rally with Rounding!

Making Smart Guesses with Numbers!

Sometimes we don't need an exact number, just a close one.

Think about:

  • How many people are at a concert?
  • How much money will groceries cost (about)?

This is called estimation or rounding!

Welcome students and introduce the concept of 'smart guesses' or estimation in daily life.

What is Rounding?

Rounding means finding a number that is close to the exact number, but easier to work with.

We usually round to the nearest 10, 100, 1,000, or even larger place values.

It helps us make quick estimates and check our answers!

Explain what rounding means in simple terms. Connect it to finding the 'nearest' friendly number.

The Vertical Number Line!

We can use a vertical number line to help us visualize rounding.

It shows us which 'friendly' number our number is closest to.

Let's see how it works!

Introduce the vertical number line as a visual tool for rounding. Explain how it helps identify which multiple of ten/hundred/thousand a number is closest to.

Rounding to the Nearest 10

Example: Round 43 to the nearest 10.

  • Step 1: Identify the tens place (the 4 in 43).

  • Step 2: What are the two multiples of 10 that 43 is between?

    • 40 (lower bound)
    • 50 (upper bound)

  • Step 3: What's the halfway point (midpoint) between 40 and 50?

    • 45

  • Step 4: Place 43 on the number line. Is it above or below the midpoint?

    • 43 is below 45, so 43 rounds down to 40.

Guide students through an example of rounding to the nearest ten using a vertical number line. Emphasize the lower bound, upper bound, and midpoint.

Rounding to the Nearest 100

Example: Round 372 to the nearest 100.

  • Step 1: Identify the hundreds place (the 3 in 372).

  • Step 2: What are the two multiples of 100 that 372 is between?

    • 300 (lower bound)
    • 400 (upper bound)

  • Step 3: What's the halfway point (midpoint) between 300 and 400?

    • 350

  • Step 4: Place 372 on the number line. Is it above or below the midpoint?

    • 372 is above 350, so 372 rounds up to 400.

Guide students through an example of rounding to the nearest hundred using a vertical number line. Highlight identifying the rounding place and the digit to the right.

The Midpoint Rule!

When do we round up, and when do we round down?

  • Look at the digit to the right of the place you are rounding to.

  • If that digit is 5, 6, 7, 8, or 9 (5 or more), you round up!

    • (The digit in the rounding place increases by one, and all digits to the right become zeros).

  • If that digit is 0, 1, 2, 3, or 4 (4 or less), you round down!

    • (The digit in the rounding place stays the same, and all digits to the right become zeros).

Emphasize the '5 or more, raise the score' rule and '4 or less, let it rest' rule. This is crucial for students to remember.

Rounding to the Nearest 1,000

Example: Round 1,499 to the nearest 1,000.

  • Step 1: Identify the thousands place (the 1 in 1,499).

  • Step 2: What are the two multiples of 1,000 that 1,499 is between?

    • 1,000 (lower bound)
    • 2,000 (upper bound)

  • Step 3: What's the halfway point (midpoint) between 1,000 and 2,000?

    • 1,500

  • Step 4: Place 1,499 on the number line. Is it above or below the midpoint?

    • 1,499 is below 1,500, so 1,499 rounds down to 1,000.

Example 2: Round 7,501 to the nearest 1,000.

  • 7,501 is above the midpoint (7,500), so it rounds up to 8,000.

Provide an example rounding to the nearest thousand. Reinforce the steps and the midpoint rule.

You're a Rounding Rock Star!

You now have a great strategy to make smart guesses with numbers!

Keep practicing, and you'll be a rounding expert in no time!

Questions?

Conclude the lesson by reiterating the importance of rounding and encouraging students to practice.

lenny

Worksheet

Rally with Rounding: Practice Time!

Directions: Round each number to the given place value. Use a vertical number line if it helps you visualize!

  1. Round 3,472 to the nearest hundred.






  2. Round 6,815 to the nearest thousand.






  3. Round 45,299 to the nearest thousand.






  4. Round 9,058 to the nearest ten.






  5. Round 12,500 to the nearest hundred.






  6. Round 789 to the nearest hundred.






  7. Round 23,456 to the nearest ten thousand.






  8. Round 5,555 to the nearest hundred.






  9. Round 99,876 to the nearest thousand.






  10. Round 1,001 to the nearest ten.






lenny
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Answer Key

Rally with Rounding: Answer Key

Directions: Round each number to the given place value. Below are the correct answers and the thought process.

  1. Round 3,472 to the nearest hundred.

    • Thought Process: The hundreds digit is 4. Look at the digit to its right, which is 7. Since 7 is 5 or more, we round up. The 4 becomes 5, and the digits to the right become zeros.
    • Answer: 3,500

  2. Round 6,815 to the nearest thousand.

    • Thought Process: The thousands digit is 6. Look at the digit to its right, which is 8. Since 8 is 5 or more, we round up. The 6 becomes 7, and the digits to the right become zeros.
    • Answer: 7,000

  3. Round 45,299 to the nearest thousand.

    • Thought Process: The thousands digit is 5. Look at the digit to its right, which is 2. Since 2 is less than 5, we round down. The 5 stays the same, and the digits to the right become zeros.
    • Answer: 45,000

  4. Round 9,058 to the nearest ten.

    • Thought Process: The tens digit is 5. Look at the digit to its right, which is 8. Since 8 is 5 or more, we round up. The 5 becomes 6, and the digit to the right becomes a zero.
    • Answer: 9,060

  5. Round 12,500 to the nearest hundred.

    • Thought Process: The hundreds digit is 5. Look at the digit to its right, which is 0. Since 0 is less than 5, we round down. The 5 stays the same, and the digits to the right become zeros.
    • Answer: 12,500

  6. Round 789 to the nearest hundred.

    • Thought Process: The hundreds digit is 7. Look at the digit to its right, which is 8. Since 8 is 5 or more, we round up. The 7 becomes 8, and the digits to the right become zeros.
    • Answer: 800

  7. Round 23,456 to the nearest ten thousand.

    • Thought Process: The ten thousands digit is 2. Look at the digit to its right, which is 3. Since 3 is less than 5, we round down. The 2 stays the same, and the digits to the right become zeros.
    • Answer: 20,000

  8. Round 5,555 to the nearest hundred.

    • Thought Process: The hundreds digit is 5. Look at the digit to its right, which is 5. Since 5 is 5 or more, we round up. The 5 becomes 6, and the digits to the right become zeros.
    • Answer: 5,600

  9. Round 99,876 to the nearest thousand.

    • Thought Process: The thousands digit is 9. Look at the digit to its right, which is 8. Since 8 is 5 or more, we round up. The 9 in the thousands place becomes a 0, and we carry over to the ten thousands place, making the 9 in the ten thousands place a 10. So, it becomes 100,000.
    • Answer: 100,000

  10. Round 1,001 to the nearest ten.

    • Thought Process: The tens digit is 0. Look at the digit to its right, which is 1. Since 1 is less than 5, we round down. The 0 stays the same, and the digit to the right becomes a zero.
    • Answer: 1,000
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