Decimals

Grade 6 · Mathematics

Semester 1 | Period 3 | Week 17

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Subject: Mathematics

Semester: 1

Period: 3

Week: 17

School Name:
Teacher’s Name:
Subject: Mathematics
Grade Level: Grade 6
Date: Week 17
Lesson Duration: 45 minutes
Week & Period: Week 17, Period 3
Topic: Decimals
Sub-topic: Rounding Off Decimals

Learning Objectives
By the end of the lesson, students should be able to:

  • Define rounding of decimals.
  • Apply rules for rounding decimals to the nearest tenth, hundredth, and thousandth.
  • Solve problems involving rounding of decimals.
  • Use rounding in real-life contexts.

Previous Knowledge
Students already know place value of decimals and four basic operations.

Instructional Materials
Mathematics textbook for Grade 6, number line charts, thermometer scales, measuring tapes.

Lesson Development – ABC Model
A – Anticipation (Warm-up / Starter)
Time: 5–10 minutes
Teacher asks: If a book costs L$7.845, how will you approximate its price for quick calculation?

B – Building Knowledge (Main Lesson Body)

Time: 25–30 minutes

  1. Definition of Rounding
  • Rounding is the process of approximating a number to make it simpler, while keeping it close in value to the original number.
  • It is often used in daily life when exact values are not needed, such as in money, measurements, and estimations.
  1. General Rules for Rounding Decimals
  2. Identify the place value you are rounding to (tenth, hundredth, thousandth, etc.).
  3. Look at the digit immediately to the right of that place.
  4. If that digit is 5 or more, increase the digit in the rounding place by 1 (round up).
  5. If that digit is less than 5, keep the digit in the rounding place the same (round down).
  6. Drop all digits after the rounding place.
  7. Worked Examples

Rounding to the Nearest Tenth (1 decimal place):

  • 4.36 → 4.4 (since 6 ≥ 5, round 3 up to 4).
  • 9.746 → 9.7 (since 4 < 5, keep 7 as it is).

Rounding to the Nearest Hundredth (2 decimal places):

  • 7.845 → 7.85 (since 5 ≥ 5, round 4 up to 5).
  • 15.678 → 15.68 (since 8 ≥ 5, round 7 up to 8).

Rounding to the Nearest Thousandth (3 decimal places):

  • 12.6789 → 12.679 (since 9 ≥ 5, round 8 up to 9).
  • 20.4572 → 20.457 (since 2 < 5, keep 7 as it is).

Extra Examples:

  • 18.999 → 19.0 (rounding up causes carrying).
  • 3.444 → 3.44 (nearest hundredth).
  • 0.7642 → 0.764 (nearest thousandth).
  • 125.5555 → 125.556 (nearest thousandth).
  1. Word Problems

Example 1 – Money:
A dress costs L$4.678. Round to the nearest tenth of a naira.
→ L$4.678 ≈ L$4.7.

Example 2 – Measurement:
The length of a rope is 12.845 m. Round it to the nearest hundredth.
→ 12.85 m.

Example 3 – Temperature:
The recorded temperature is 36.457°C. Round to the nearest tenth.
→ 36.5°C.

Example 4 – Estimation for Shopping:
Mary bought items costing L$2.36, L$4.78, and L$1.95. Round each to the nearest tenth before adding.
→ 2.4 + 4.8 + 2.0 = L$9.2 (estimate).

 

  1. Learners’ Activities (Expanded)
  • Learners round given decimals to tenth, hundredth, and thousandth on the board.
  • Group activity: learners collect prices of goods (real or imagined) and round them to the nearest tenth before totaling.
  • Learners use thermometers (or given data) and round recorded temperatures.
  • Peer activity: learners create 3 decimal numbers each and exchange with classmates to round.

 

  1. Assessment Checks (Quick Questions)
  2. Round off 9.746 to the nearest tenth.
  3. Round off 15.678 to the nearest hundredth.
  4. Round off 20.4572 to the nearest thousandth.
  5. The cost of a pen is L$5.894. Round to the nearest tenth.
  6. A distance is 13.457 km. Round to the nearest hundredth.

 

  1. Notes (Expanded & Detailed)
  • Rounding helps to simplify calculations and make numbers easier to understand.
  • It is widely used in:
    • Shopping – rounding prices to estimate total costs.
    • Measurement – rounding lengths, weights, or capacities to practical levels.
    • Science and temperature – recording and reporting results in simpler forms.
  • Remember: round up if digit is 5 or more; round down if less than 5.

 

  1. Assignment
  2. Round each to the nearest tenth:
    • 67, 8.25, 12.98, 7.46.
  3. Round each to the nearest hundredth:
    • 678, 14.239, 9.999.
  4. Round each to the nearest thousandth:
    • 8765, 25.3456, 18.1234.
  5. Word Problems:
    A bag of rice weighs 49.856 kg. Round to the nearest tenth.
    ii. A student scored 78.456 marks. Round to the nearest hundredth.
    iii. A piece of wood is 3.4567 m long. Round to the nearest thousandth.

C – Consolidation (Conclusion & Assessment)
Time: 5–10 minutes
Summary: Students learn rules of rounding and practice applying them in real-life contexts.

Evaluation Method (Expanded)
Exit slip/quiz: Round off 2.349 to nearest tenth, 6.782 to nearest hundredth.
Teacher will collect slips and provide oral feedback.

Assignment (Expanded):
Round off 14.3567 to nearest tenth, hundredth, and thousandth.

Follow-up Activity:
Students practice rounding real-life measurements (weight, height, temperature).

Differentiation / Inclusive Strategies
Use number lines for visual learners; allow advanced learners to solve word problems involving rounded data.

Teacher’s Reflection (After Class)
What worked well? ___________________________________________
What needs improvement? ____________________________________
Students’ engagement level: ☑ High ☑ Medium ☑ Low