Squares And Rectangles Basic 3 Mathematics Lesson Note

A. COUNTING SKILL: NUMBERS 881-900

Counting from 881 to 900: 881, 882, 883, 884, 885, 886, 887, 888, 889, 890, 891, 892, 893, 894, 895, 896, 897, 898, 899, 900

Special milestone: 900 = Nine hundred

Practice counting:

• From 885 to 895: _______
• From 892 to 900: _______
• Backwards from 900 to 890: _______

Fill in missing numbers:

• 886, 887, _____, 889, _____
• 895, _____, 897, _____, 899
• _____, 882, _____, 884, _____

B. WRITING SKILL: WRITING OF THE NUMBERS

Write in words:

• 881 = Eight hundred and eighty-one
• 885 = Eight hundred and eighty-five
• 890 = Eight hundred and ninety
• 895 = Eight hundred and ninety-five
• 900 = Nine hundred

Write in figures:

• Eight hundred and eighty-three = _______
• Eight hundred and eighty-eight = _______
• Eight hundred and ninety-two = _______
• Eight hundred and ninety-seven = _______
• Eight hundred and ninety-nine = _______

C. COMPARING SIZES OF SIMILAR OBJECTS

What does “similar” mean? Similar objects have the same shape but different sizes.

Examples of similar objects:

• Two squares (one big, one small)
• Two rectangles (one long, one short)
• Two books (one thick, one thin)

Comparing squares: Square A: side = 3cm Square B: side = 5cm Square B is bigger than Square A.

Comparing rectangles: Rectangle A: 4cm × 2cm Rectangle B: 6cm × 3cm Rectangle B is bigger than Rectangle A.

Practice comparing:

1. Square with side 4cm vs Square with side 7cm Which is bigger? _______
2. Rectangle 5cm × 3cm vs Rectangle 8cm × 4cm Which is bigger? _______
3. Circle the bigger shape:
   1. Square 6cm × 6cm OR Rectangle 8cm × 2cm

D. INTRODUCTION TO AREA

What is area? Area is the space inside a shape. Area tells us how much space a shape covers.

Unit square: We measure area using unit squares. A unit square is a square with sides of 1 unit (1cm × 1cm).

How to find area: Count how many unit squares fit inside the shape.

Example:

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This rectangle has 6 unit squares. Area = 6 square units.

Area vs Perimeter:

• Perimeter = distance around the shape
• Area = space inside the shape

Practice identifying:

1. Going around a garden = _______ (perimeter/area)
2. Painting a wall = _______ (perimeter/area)
3. Putting fence around a field = _______ (perimeter/area)
4. Covering floor with tiles = _______ (perimeter/area)

E. COMPARING UNIT SQUARES TO OBTAIN AREA

Finding area of squares:

Square with side 2cm:

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Area = 4 square cm (or 4 cm²)

Square with side 3cm:

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Area = 9 square cm (or 9 cm²)

Pattern for squares:

• Side 1cm: Area = 1 × 1 = 1 cm²
• Side 2cm: Area = 2 × 2 = 4 cm²
• Side 3cm: Area = 3 × 3 = 9 cm²

Practice finding area of squares:

1. Square side 4cm: Area = 4 × 4 = _____ cm²
2. Square side 5cm: Area = _____ cm²
3. Square side 6cm: Area = _____ cm²

Finding area of rectangles:

Rectangle 3cm × 2cm:

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Area = 3 × 2 = 6 cm²

Rectangle 4cm × 3cm:

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Area = 4 × 3 = 12 cm²

Formula:

• Square area = side × side
• Rectangle area = length × width

Practice finding area of rectangles:

1. Rectangle 5cm × 3cm: Area = 5 × 3 = _____ cm²
2. Rectangle 6cm × 2cm: Area = _____ cm²
3. Rectangle 4cm × 4cm: Area = _____ cm²

F. QUANTITATIVE REASONING

Word problems:

1. A square tile has sides of 8cm. What is its area?
2. A rectangular carpet is 5m long and 3m wide. What area does it cover?
3. Kemi’s exercise book cover is 20cm long and 15cm wide. What is the area of the cover?
4. A square garden has sides of 12m. What is the area of the garden?

Comparison problems:

1. Which has bigger area?
   • Square with side 6cm OR Rectangle 8cm × 4cm?
2. Square 5cm × 5cm OR Rectangle 7cm × 3cm?
3. Rectangle 10cm × 2cm OR Square 4cm × 4cm?

Area and perimeter together:

1. A square has perimeter 16cm. What is its area? (Hint: Find the side first)
2. A rectangle has area 24 cm² and length 6cm. What is its width?

Real-life applications:

1. A farmer wants to plant grass on a rectangular field 30m × 20m. How much area needs grass?
2. Floor tiles are 1m × 1m each. How many tiles are needed for a square room with sides 8m?
3. A rectangular swimming pool is 25m long and 10m wide. What is the area of the pool?

Pattern recognition:

1. Areas of squares: 1cm², 4cm², 9cm², _____, _____
2. Rectangle areas: 2×1=2, 3×1=3, 4×1=4, 5×1=_____

CLASS EXERCISES

1. Count from 888 to 898:
2. Write in words:
   1. 887 = _______
   2. 893 = _______
   3. 900 = _______
3. Compare shapes:
   1. Square side 5cm vs Square side 8cm. Which is bigger? _______
   2. Rectangle 6cm×4cm vs Rectangle 7cm×3cm. Which has bigger area? _______
4. Find areas of squares:
   1. Square side 7cm: Area = _____ cm²
   2. Square side 9cm: Area = _____ cm²
5. Find areas of rectangles:
   1. Rectangle 8cm × 5cm: Area = _____ cm²
   2. Rectangle 12cm × 3cm: Area = _____ cm²
6. Area or perimeter?
   1. Putting ribbon around a picture frame: _______
   2. Covering a table with cloth: _______
   3. Walking around a field: _______
7. Word problems:
   1. A square playground has sides of 15m. What is its area?
   2. A rectangular classroom is 8m long and 6m wide. What is the area?
8. Compare areas:
   1. Square 6cm × 6cm OR Rectangle 9cm × 4cm? Which is bigger? _______
9. Mixed problems:
   1. A rectangle has area 35 cm² and length 7cm. What is the width?
   2. A square has perimeter 20cm. What is its area?
10. Problem solving: A rectangular garden is divided into square plots of 2m × 2m each. If the garden is 12m long and 8m wide, how many square plots are there?