Compound Shapes Area Perimeter Demonstration This resource provides

Compound Shapes – Area & Perimeter – Demonstration This resource provides animated demonstrations of the mathematical method. Check animations and delete slides not needed for your class.

Farmer Ann builds 2 pig-pens using fencing. How big is each pig pen? How much fencing was used for each pig pen? 1 m Area = 6 m 2 Perimeter = 10 m 1 m 2 Area = 5 m 2 Perimeter = 10 m

For every polygon (flat shape) we can find the size of… the area (the surface) Imagine: the space to move Area = 6 m 2 & the perimeter (the edge) Imagine: walking around the outside Perimeter = 10 m 1 m 1 m 2

These are compound shapes, they are made up of 2 or more rectangles or squares. How would you divide the shapes into parts? overlapping

1 cm How many different shapes can you draw with a perimeter of 10 cm 2 ? 1 cm 2 What is the area of each shape? 4 cm 2 6 cm 2 5 cm 2 4 cm 2 Why don’t these shapes have a pair? 4 cm 2

How can we find the missing lengths in these diagrams? 2 6 6? 3 9? 8 8? 12 4 (not drawn accurately) 10 7 4? 7

Calculate the area & perimeter of this compound shape. 1) Divide the compound shape into rectangles. 2) Calculate & label missing lengths. Area: (Add the shape areas) 2 cm 2× 2=4 2× 4=8 2 cm Total = 4 + 8 = 12 cm 2 4 cm Perimeter: (‘Walk’ around the outside) 2 cm 2+2+2+4+4+2 4 cm = 16 cm

Calculate the area & perimeter of this compound shape. 1) Divide the compound shape into rectangles. 2) Calculate & label missing lengths. Area: (Add the shape areas) 5 cm 4 × 5 = 20 2× 2=4 4 cm Total = 20 + 4 = 24 cm 2 6 cm Perimeter: (‘Walk’ around the outside) 3 cm 2 cm 5+6+2+2+3+4 2 cm = 22 cm

Calculate the area & perimeter of this compound shape. 1) Divide the compound shape into rectangles. 2) Calculate & label missing lengths. Area: (Add the shape areas) 8 × 4 = 32 4 cm 6 × 5 = 30 Total = 32 + 30 = 62 cm 2 3 cm 8 cm 6 cm 5 cm Perimeter: (‘Walk’ around the outside) 4 + 3 + 6 + 5 + 10 + 8 10 cm = 36 cm

Calculate the area & perimeter of this compound shape. 1) Divide the compound shape into rectangles. 2) Calculate & label missing lengths. 3 cm Area: (Add the shape areas) 4 × 4 = 16 3 × 9 = 27 5 cm 4 cm Total = 16 + 27 = 43 cm 2 9 cm Perimeter: (‘Walk’ around the outside) 4 cm 4+5+3+9+7+4 7 cm = 32 cm

Calculate the area & perimeter of this compound shape. 1) Divide the compound shape into rectangles. 2) Calculate & label missing lengths. Area: (Add the shape areas) 4 × 5 = 20 4 cm 3 × 10 = 30 Total = 20 + 30 = 50 cm 2 5 cm 2 cm 4 cm 8 cm Perimeter: (‘Walk’ around the outside) 3 cm 2 + 5 + 4 + 3 + 10 + 3 10 cm = 36 cm

Perimeter: What’s the same, what’s different? 10 cm 12 cm

2 cm Calculate the area & perimeter of each compound shape. 3 cm A) 3 cm B) Area = 32 cm 2 Perimeter = 36 cm 3 cm 6 cm Area = 27 Perimeter = 24 cm 3 cm cm 2 10 cm 2 cm 8 cm 6 cm 8 cm C) 2 cm 5 cm Area = 25 cm 2 Perimeter = 26 cm 3 cm 9 m D) 9 m Area = 57 m 2 Perimeter = 44 m 3 m 2 m

Questions? Comments? Suggestions? …or have you found a mistake!? Any feedback would be appreciated . Please feel free to email: tom@goteachmaths. co. uk