Rounding Numbers

Curriculum Area

Mathematics and Statistics – Number and Algebra
Curriculum Level: Level 2 (Year 3)
Strand: Number and Algebra
Achievement Objective:

• Number Knowledge: Know how many ones, tens, and hundreds are in whole numbers up to at least 1,000.
• Number Strategies: Solve problems by using place value and rounding.

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Lesson Overview

Title: Rounding Numbers to the Nearest Ten
Unit: Estimating Collections: Tens (Lesson 2 of 5)
Lesson Duration: 60 minutes
Class Size: 26 students
Learning Intentions:

• Understand the concept of rounding to the nearest ten.
• Use number lines and visual strategies to help round numbers.
• Apply rounding concepts in practical and engaging activities.

Success Criteria:

• I can identify the nearest tens for different numbers.
• I can use a number line to help me round a number correctly.
• I can explain my rounding decisions to a peer or teacher.

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Materials and Preparation

• Whiteboard & Markers
• Class Set of Mini Whiteboards & Markers
• Large Number Line (0-100) for class display
• Individual Number Lines (printed and laminated for students)
• Place Value Blocks or Counting Objects
• Printed Rounding Charts (showing key numbers and rounding rules)
• Digital Timer for activities

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Lesson Breakdown

1. Introduction (10 minutes) - Warming Up the Brain

Hook: Start with a fun estimation activity.

• Show a clear jar with small items (e.g., buttons, beads) and ask: "Do you think there are closer to 40 or 50 in the jar? Why?"
• Encourage students to discuss their guesses with a partner before sharing with the class.
• Briefly introduce rounding: "Today, we’re going to learn how to round numbers to the nearest ten, to help us make quick and smart estimations!"

2. Explicit Teaching (15 Minutes) - Exploring Rounding

Teacher Explanation:

• Write three numbers on the board (e.g., 23, 47, 68).
• Draw a number line from 20 to 30 for the first example (23) and use a marker to place 23 on it.
• Ask: "What are the closest tens to 23?" (20 and 30)
• Explain the rounding rule:
  • Numbers below 5 round down to the lower ten.
  • Numbers 5 or higher round up to the next ten.
• Model rounding 47 and 68 together, using the number line.

Student Participation:

• Hand out individual number lines to students.
• Have them plot the numbers 12, 38, 54, and 79 and round them independently.
• Ask a few students to share how they rounded and explain their thinking.

3. Guided Practice (15 minutes) - Hands-On & Peer Learning

Game: "Rounding Relay"

1. Split students into pairs, giving each pair a mini whiteboard.
2. Teacher calls out a number (e.g., 33).
3. Pairs work together to quickly write:
   • The tens the number falls between.
   • Whether the number rounds up or down.
   • The rounded number.
4. One partner does the first problem, and the other partner checks.
5. Rotate roles and continue with 5 more numbers.

Differentiation:

• Support: Provide number line templates for students who need extra help.
• Extension: Challenge faster students by using 3-digit numbers (e.g., 127 → rounds to 130).

4. Independent Practice (15 minutes) - Applying Learning

Activity: "Rounding Treasure Hunt"

• Around the classroom, place cards with numbers (e.g., 21, 44, 72).
• Students walk around with a sheet, find the numbers, and round them to the nearest ten.
• They write their answers in a table and check their results with a partner.

5. Reflection & Wrap-Up (5 minutes) - Bringing It All Together

• Ask: "Why do we round numbers? When might rounding be useful in real life?"
• Share examples:
  • Estimating how much something costs.
  • Quickly checking if you have enough objects.

💡 Exit Ticket:

• On a sticky note, each student writes 1 number of their choice (1–99).
• They round it to the nearest ten and stick it on the class rounding chart.
• Collect and review patterns and understanding.

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Assessment & Next Steps

• Formative Assessment: Observe students’ responses on their mini whiteboards and during partner activities.
• Next Lesson Preview: Students will learn how rounding applies to real-world problems, like estimating costs in shopping.

🔹 Key Reflection for Teachers: What worked well today? Did students struggle with any particular step? What could be adjusted in future lessons?

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Teacher Notes

• Ensure plenty of movement and hands-on activities to maintain engagement.
• Encourage verbal reasoning—ask students to explain why they rounded up or down.
• Adjust timing based on student needs; slow down if necessary for struggling learners.

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This lesson is designed to align with the New Zealand Curriculum and engage Year 3 students in meaningful, interactive maths learning. 🙌 Happy teaching! 🚀