🌟 Surface Area Introduction 🌟

Hi my wonderful Grade 6 friends! 👋

Today we’re learning about Surface Area! Surface area is the total area of all the outside faces of a 3D shape. It’s like wrapping a present — you need to know how much paper to cover the whole outside!

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1. What is Surface Area?

Surface Area = Sum of the areas of ALL faces

For a rectangular prism (box), we add the area of the front, back, left, right, top, and bottom.

Front
Back
Right
Left
Top
Bottom

2. Formula for Rectangular Prism

Surface Area = 2(lw + lh + wh)
Where:
l = length, w = width, h = height

This formula adds up all six faces at once!

3. Step-by-Step Examples

Example 1: A box is 5 cm long, 4 cm wide, 3 cm high.
SA = 2(5×4 + 5×3 + 4×3) = 2(20 + 15 + 12) = 2(47) = 94 cm²

Example 2: A room is 6 m long, 5 m wide, 3 m high.
SA = 2(6×5 + 6×3 + 5×3) = 2(30 + 18 + 15) = 2(63) = 126 m²

4. Let’s Practice Together! 🎉

Question 1

A gift box is 8 cm long, 6 cm wide, and 4 cm high. What is its surface area?

208 cm²
2(8×6 + 8×4 + 6×4) = 2(48+32+24) = 208 ⭐

Question 2

A cereal box is 30 cm tall, 20 cm long, and 8 cm wide. Find the surface area.

1520 cm ²
2(30×20 + 30×8 + 20×8) = 2(600+240+160) = 2000? Wait, let me correct: actually 2(600 + 240 + 160) = 2×1000 = 2000 cm² ⭐

Question 3

Why do we multiply by 2 in the formula?

Because there are two of each pair of opposite faces! ⭐

5. Surface Area in Real Life 🇨🇦

• Wrapping gifts at Christmas
• Painting the walls and ceiling of a room
• Making cardboard boxes for shipping
• Calculating material needed for tents or canopies
• Designing packaging for products

You are now a Surface Area Explorer! 🌟

Great work today! You understand what surface area is and how to calculate it for rectangular prisms.

Next time you wrap a gift or paint a box, think about surface area!

Love and proud high-fives,
Mrs. Brenda ❤️

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