Thurs 13th Oct – Surface Area of a Cuboid

LEARNING OBJECTIVE: To understand what is meant by the surface area of a cuboid and work out the total surface area of a cuboid

SUCCESS CRITERIA: You will be able to explain to someone what the surface area of a cuboid is and be able to work out the total surface area of a cuboid if you know its length, width and height.

STARTER: Work out the area of these rectangles

1. Length 4cm, width 5cm, Area = 20 cm2
   
2. Length 12cm, width 7cm, Area = 84 cm2
   
3. Length 2.5m, width 6m, Area = 15 m2
   
4. Length 5m, width 2.4m, Area = 12 m2
   
5. Length 2.6 cm, width 1.4m, Area = 3.64 cm2
   
6. Length 4.3cm, width 5.6cm, Area = 24.08 cm2
   
7. Length 420m, width 565m Area = 237,300m²
   

LESSON: Use screens 1 and 2 from this Mymaths lesson to introduce the idea of unfolding a cube

Use next two screens to look at unfolding a cuboid.

Use The IWB To Look at a 3cm x 5cm x 6cm cuboid and show how to unfold it and work out the area of each face. Then add up all six faces.

Repeat with another example if necessary

Work through Surface area of Cuboids worksheet

EXTENSION QUESTIONS:

1. Without drawing the net can you work out the Surface area of a cube 5cm or 8cm or 12cm
   
2. Can you write down a rule to work out the surface area of any cube
   

PLENARY: Check student's answers. Use five finger feedback for

1. Unfolding a cuboid (working out the net),

2. Working out the surface area of a cuboid.