Mathematics - Junior Secondary 1 - Approximation continued

Approximation continued

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TERM: 2ND TERM

WEEK 2

Class: Junior Secondary School 1
Age: 12 years
Duration: 40 minutes of 5 periods
Subject: Mathematics
Topic: Approximation Continued
Focus: Approximating in Operations and Quantitative Reasoning

SPECIFIC OBJECTIVES:

By the end of the lesson, pupils should be able to:

  1. Use approximation in addition, subtraction, multiplication, and division.
  2. Approximate values before and after solving.
  3. Estimate answers mentally using rounding.
  4. Solve real-life problems using quantitative reasoning and approximation.
  5. Relate approximation to daily life scenarios.

 

INSTRUCTIONAL TECHNIQUES:

  • Direct teaching
  • Questioning
  • Guided calculations
  • Group activities
  • Real-life simulation

 

INSTRUCTIONAL MATERIALS:

  • Flashcards
  • Place value charts
  • Number lines
  • Worksheets
  • Newspaper cuttings
  • Whiteboard & marker

 

PERIOD 1 & 2: Approximating in Operations

PRESENTATION:

Step

Teacher’s Activity

Pupil’s Activity

Step 1 – Introduction

Recaps rounding and s.f, introduces operations with approximation.

Pupils review and ask questions

Step 2 – Demonstration

Works through examples in addition/subtraction with rounding.

Pupils solve along with teacher

Step 3 – Practice

Gives real-life scenarios for estimating totals/costs/values.

Pupils estimate and calculate

Step 4 - Note Taking

Summarizes method: round → operate → estimate answer.

Pupils take notes

NOTE ON BOARD:

  • 68 + 124 ≈ 70 + 120 = 190 (estimated)
  • 398 – 112 ≈ 400 – 100 = 300
  • 21.3 × 4.7 ≈ 21 × 5 = 105
  • Use approximation for quick mental math and real-life decisions

EVALUATION (5 questions):

  1. Approximate and add: 45 + 78
  2. Approximate and subtract: 892 – 238
  3. Multiply using rounded values: 12.4 × 5.6
  4. Divide using rounded values: 89 ÷ 4.5
  5. Round and estimate: 21.6 + 17.9

CLASSWORK (5 tasks):

  1. 66 + 77 (estimate)
  2. 455 – 198 (estimate)
  3. 8 × 2.1 (round, then multiply)
  4. 9 ÷ 2.2 (approximate)
  5. 105 + 298 (round and solve)

ASSIGNMENT (5 tasks):

  1. Write 3 operations and round each number involved.
  2. Estimate and solve each.
  3. Compare your estimates with actual values.
  4. State the difference.
  5. Reflect: When is estimation useful?

 

PERIOD 3 & 4: Quantitative Reasoning & Real-life Use

PRESENTATION:

Step

Teacher’s Activity

Pupil’s Activity

Step 1 - Introduction

Discusses estimating in shopping, cooking, budgeting, etc.

Pupils give examples

Step 2 - Scenarios

Provides real-life word problems needing approximation.

Pupils work in groups to solve

Step 3 - Practice

Pupils solve multi-step problems with rounding.

Pupils practice and share results

EVALUATION (5 questions):

  1. You bought 3 items costing ₦289, ₦345, and ₦120. Estimate total cost.
  2. A school has 1,345 boys and 1,420 girls. Approximate total number of students.
  3. Round 4.9 and 2.7, then multiply.
  4. Round ₦4,765 to the nearest hundred.
  5. Estimate how many books can be bought with ₦10,000 if each is ₦1,678.

CLASSWORK (5 tasks):

  1. Round 349, 428, and 199. Add all.
  2. Estimate cost of 5 items: ₦199, ₦345, ₦120, ₦89, ₦478
  3. Approximate area: 12.5 m × 8.9 m
  4. Round 9.85 to 1 decimal place
  5. Estimate savings after spending ₦4,750 out of ₦10,000

ASSIGNMENT (5 tasks):

  1. Find 3 real-life numbers (food, transport, airtime).
  2. Round each to nearest hundred.
  3. Estimate total spending.
  4. Compare with actual total.

Write a short paragraph on the importance of approximation.