Lesson Plan
Round to the Nearest Ten?
Students will be able to round two-digit numbers to the nearest ten using number lines and place value strategies.
Rounding helps us estimate numbers quickly and makes mental math easier. It's a useful skill in everyday life, like when you're estimating costs or distances!
Audience
2nd Grade, Small Group
Time
30 minutes
Approach
Interactive instruction, guided practice, and independent application.
Materials
Whiteboard or chart paper, Markers, Eraser, Optional: Individual whiteboards and markers for students, Rounding to the Tens Slide Deck, Rounding Practice Worksheet, and Rounding Practice Answer Key
Prep
Teacher Preparation
10 minutes
- Review the Rounding to the Tens Slide Deck and practice explaining the concepts.
- Print copies of the Rounding Practice Worksheet and Rounding Practice Answer Key.
- Prepare a blank number line on the whiteboard or chart paper for demonstration.
- Gather any optional materials like individual whiteboards for students.
- Familiarize yourself with the script for smooth delivery.
Step 1
Warm-Up: Counting by Tens
3 minutes
- Teacher Script: "Hello mathematicians! To get our brains warmed up, let's count by tens together, starting from 0 all the way to 100. Ready?"
* Lead students in counting aloud by tens: 0, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100.
Step 2
Introduction: What is Rounding?
5 minutes
- Teacher Script: "Today, we're going to learn about something super helpful called 'rounding to the nearest ten.' Has anyone heard of rounding before? It's like finding the 'neighboring ten' that a number is closest to! We do this to make numbers easier to work with."
Step 3
Modeling with a Number Line
8 minutes
- Teacher Script: "Let's use a number line to help us. Imagine we have the number 23. What two tens is 23 between? (Guide students to 20 and 30). Which ten is 23 closer to? How can we tell?"
* Display Rounding to the Tens Slide Deck slide 2.
* Use a physical number line (whiteboard or chart paper) to visually demonstrate placing 23 and identifying the nearest ten. Repeat with 27 (closer to 30).
* Teacher Script: "Here's a trick: if the ones digit is 5 or more (5, 6, 7, 8, 9), we round UP to the next ten. If it's less than 5 (0, 1, 2, 3, 4), we round DOWN to the lower ten."
* Display Rounding to the Tens Slide Deck slide 3.
Step 4
Guided Practice: Rounding Together
7 minutes
- Teacher Script: "Now let's try a few together. I'll write a number, and you tell me what ten it rounds to and why. Think about our number line and our 'rule of 5'."
* Display Rounding to the Tens Slide Deck slide 4.
* Present numbers like 31, 38, 45, 12, 19. For each number, ask:
* "What two tens is this number between?"
* "What is the ones digit?"
* "Does it round up or down?"
* "What is the nearest ten?"
* Encourage students to explain their reasoning.
Step 5
Independent Practice: Worksheet Time
5 minutes
- Teacher Script: "Great job everyone! Now it's your turn to show what you've learned. I'm handing out a Rounding Practice Worksheet. Work quietly on your own, and if you get stuck, remember our number line strategy and the 'rule of 5'."
* Distribute the Rounding Practice Worksheet. Circulate to provide support as needed.
Step 6
Cool-Down: Quick Check
2 minutes
- Teacher Script: "Alright, put your pencils down for a moment. For our cool-down, I want each of you to tell me one number you rounded today and what ten it rounded to. Or, tell me why rounding is important!"
* Have each student share one example or thought.
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Slide Deck
Welcome, Rounding Rockstars!
Today, we're going to learn how to round numbers to the nearest ten.
It's like finding a number's 'closest ten-friend'!
Welcome students and briefly introduce the concept of rounding as making numbers 'friendlier' or easier to work with. Explain that today we'll focus on rounding to the nearest ten.
Meet the Number Line!
Numbers live between two tens!
Where does 23 live?
Between 20 and 30
Is 23 closer to 20 or 30?
Where does 27 live?
Between 20 and 30
Is 27 closer to 20 or 30?
Explain that numbers live between tens. Use the number line to show where a number like 23 or 27 would sit. Emphasize finding the 'halfway' point (e.g., 25). Visually demonstrate which ten is closer.
The 'Rule of 5' Shortcut
Look at the ones digit!
- If it's 5 or more (5, 6, 7, 8, 9), round UP to the next ten.
- If it's less than 5 (0, 1, 2, 3, 4), round DOWN to the lower ten.
Introduce the 'Rule of 5' as a shortcut or a quick way to remember without always drawing a number line. Give examples verbally.
Let's Practice Together!
What does 31 round to?
What does 38 round to?
What does 45 round to?
What does 12 round to?
What does 19 round to?
Work through a few examples with the students, using both the number line thinking and the 'Rule of 5'. Ask them to explain their reasoning.
You're a Rounding Expert!
Great job today, mathematicians!
Rounding helps us estimate and makes numbers easier to work with.
Keep practicing, and you'll be rounding like a pro!
Conclude the lesson by reminding students that rounding helps us estimate and makes numbers easier to use. Encourage them to look for opportunities to round in their daily lives.
Worksheet
Rounding to the Nearest Ten
Directions: Look at each number. Draw a small number line if it helps you! Then, round the number to the nearest ten.
- 32 rounds to __________
- 68 rounds to __________
- 45 rounds to __________
- 11 rounds to __________
- 89 rounds to __________
- 54 rounds to __________
- 76 rounds to __________
- 23 rounds to __________
- 90 rounds to __________
- 17 rounds to __________
Bonus Question!
Think of a time when you might use rounding in real life. Write it down!
Answer Key
Rounding to the Nearest Ten - Answer Key
Directions: Look at each number. Draw a small number line if it helps you! Then, round the number to the nearest ten.
- 32 rounds to 30
- Thought Process: 32 is between 30 and 40. The ones digit is 2, which is less than 5, so we round down to 30.
- Thought Process: 32 is between 30 and 40. The ones digit is 2, which is less than 5, so we round down to 30.
- 68 rounds to 70
- Thought Process: 68 is between 60 and 70. The ones digit is 8, which is 5 or more, so we round up to 70.
- Thought Process: 68 is between 60 and 70. The ones digit is 8, which is 5 or more, so we round up to 70.
- 45 rounds to 50
- Thought Process: 45 is exactly in the middle of 40 and 50. When the ones digit is 5, we always round up to the next ten, which is 50.
- Thought Process: 45 is exactly in the middle of 40 and 50. When the ones digit is 5, we always round up to the next ten, which is 50.
- 11 rounds to 10
- Thought Process: 11 is between 10 and 20. The ones digit is 1, which is less than 5, so we round down to 10.
- Thought Process: 11 is between 10 and 20. The ones digit is 1, which is less than 5, so we round down to 10.
- 89 rounds to 90
- Thought Process: 89 is between 80 and 90. The ones digit is 9, which is 5 or more, so we round up to 90.
- Thought Process: 89 is between 80 and 90. The ones digit is 9, which is 5 or more, so we round up to 90.
- 54 rounds to 50
- Thought Process: 54 is between 50 and 60. The ones digit is 4, which is less than 5, so we round down to 50.
- Thought Process: 54 is between 50 and 60. The ones digit is 4, which is less than 5, so we round down to 50.
- 76 rounds to 80
- Thought Process: 76 is between 70 and 80. The ones digit is 6, which is 5 or more, so we round up to 80.
- Thought Process: 76 is between 70 and 80. The ones digit is 6, which is 5 or more, so we round up to 80.
- 23 rounds to 20
- Thought Process: 23 is between 20 and 30. The ones digit is 3, which is less than 5, so we round down to 20.
- Thought Process: 23 is between 20 and 30. The ones digit is 3, which is less than 5, so we round down to 20.
- 90 rounds to 90
- Thought Process: 90 is already a ten, so it rounds to itself.
- Thought Process: 90 is already a ten, so it rounds to itself.
- 17 rounds to 20
- Thought Process: 17 is between 10 and 20. The ones digit is 7, which is 5 or more, so we round up to 20.
- Thought Process: 17 is between 10 and 20. The ones digit is 7, which is 5 or more, so we round up to 20.
Bonus Question!
Think of a time when you might use rounding in real life. Write it down!
- Possible Answers: Estimating how much money you need for groceries, figuring out approximately how long a trip will take, guessing how many people are at an event.