Starter

• On whiteboards, write down as many units of LENGTH as you can

• Write down as many units for AREA as you can

EXTENSION:What is the perimeter of this rectangle?

Perimeter

Learning Objectives:

Know the key words for perimeter and

the units used

Able to calculate the perimeter of a

rectangle

Able to calculate the perimeter of a

compound shape

09/04/2023

Perimeter

• Perimeter: The distance around the outside of a shape

• To calculate the perimeter, you add together all the sides of a shape

Perimeter

• Example:10cm

3cm

P = 10 + 3 + 10 + 3

P = 26cm

Perimeter

• Calculate the perimeter of the following rectangles:

12cm

4cm

5m

6m

9cm

1cm

5cm

5cm

a)

d)c)

b) EXTENSION:Can you calculate the area of these rectangles?

Perimeter

• Compound shape: a 2D shape made up of many shapes

Perimeter10m

25m

10m

31m

21m

15m

Can I calculate the perimeter of this shape?

I need to find the length of the missing sides first.

Now I can calculate the perimeter by adding up the all the sides.

P = 10 + 15 + 21 + 10 + 31 + 25

P = 112m

Perimeter

• Example:

3cm3cm

9cm 9cm

10cm

5cm

10 – 3 – 3 = 4cm

5cm as it is a rectangle

Perimeter = 5 + 10 + 5 + 3 + 9 + 4 + 9 + 3

Perimeter = 48cm

Starter

• Calculate the perimeter of the following shapes

11cm

5cm

18m

5m

4m

20m

Perimeter

Learning Objectives:

Able to calculate the perimeter of a

rectangle

Able to calculate the perimeter of a

compound shape

Able to calculate the area of a

rectangle

09/04/2023

Your turn…

• Exercise 5A, page 97

Area

• How can I calculate the area of this rectangle?

• Count the squares inside the shape

• Multiply the width by the length

Area of a rectangle

• Area of a rectangle = length x width

4cm

12cm

Area = 4 x 12

Area = 48cm2

Starter

• How many rectangles can you design that have an area of 24cm2?

• Do the sides have to be whole numbers?

Area of Triangles

Learning Objectives:

• Able to calculate the area of a rectangle

• Able to calculate the area of a triangle

• Able to calculate the area of a compound shape

09/04/2023

Area of Triangles

• Area of a triangle = ½ x base x height = ½bh

Base

Height

Area of a Triangle

• Calculate the area of this triangle.

12cm

4cm

Area = ½ x 4 x 12 = 24cm2

Area of Triangles

• Find the area of the shaded triangle BCD.5cm

6cm

4cm

11cm

A

D

CB

Area of ACD = ½ x 9 x 6 = 27cm2

Area of ABD = ½ x 5 x 6 = 15cm2

Area of BCD = 27 – 15 = 12cm2

Your turn…

• Page 104, Exercise 5E, Qs 1 to 4.

Starter

• Complete the worksheet in your workbook– Show all your working out– Remember to use the correct units!

Area of Triangles

Learning Objectives:

• Able to calculate the area of a right angled triangle

• Able to identify the perpendicular height of a triangle

• Able to calculate the area of any triangle

09/04/2023Grade D

Area of Triangles

• Perpendicular – “at right angles to”

Area of Triangles

• Area = base x height2

The perpendicular height

height

base

base

base

heightheight

Area of Triangles

• Find the area of the following triangle.

4cm

10cm

7cm6cm

Area = ½ x 10 x 6 = 30cm2

Area of Triangles

11cm15cm

9cm

12cm

5m

15m

18m8m

Area of Triangles

Learning Objectives:

• Able to calculate the area of a right-angled triangle

• Able to calculate the area of other triangles

• Able to calculate the area of a parallelogram

09/04/2023Grade D

Area of Triangles

17cm12cm

6cm 25m

20m 20m10m

5km

30km

27km

3km

1 2

3

36cm2125m2

45km2

Some work…

• In your workbooks, work through pages 65 and 66.

Home Learning

• Complete the worksheet in your books

• Show all working out

• DUE: Monday 19th September

Starter

• Match the shape to the correct area and perimeter.

• There is one perimeter and one area that don’t have a shape. Draw the shape to match the perimeter and area on the blank card.

Parallelograms and Trapezia

Learning Objectives

• Able to calculate the area of triangles

• Able to calculate the area of parallelograms and trapezia

09/04/2023Grade D

Area of a Parallelogram

12cm

9cm6cm

Area = 6 x 12 = 72cm2

Base

height

Area of Parallelogram = base x perpendicular height

Area of a Trapeziuma

b

h

Area of Trapezium = ½ (a + b) x h

a and b are the parallel sides

Starter

• Calculate the area of these trapezia.15cm

7cm

8cm8cm

14cm

12cm

Area of Compound Shapes

Learning Objectives:

• Able to calculate areas of trapezia

• Able to split up a compound shape

• Able to find the area of a compound shape

09/04/2023Grade D

Compound Shapes

• To find the area of compound shapes, split them up into their composite shapes.

• Find the area of each shape, then add them together

Compound Shapes

5cm

11cm

8cm

2cm

A

B

Area A = 8 x 5 = 40cm2

Area B = 11 x 2 = 22cm2

Total Area = 40 + 22 = 62cm2

Compound Shapes

15cm

7cm1cm

8cm

Your turn…

• Complete the worksheet in your work books.

Starter

• The rectangles below have the same area. Find the value of x.

5cm

8cm

20cm

Circles

Learning Objectives:

• Able to calculate the radius and diameter of a circle• Able to use a calculator to find the

circumference of a circle• Able to calculate the area of a circle

09/04/2023Grade D/C

Circles

• Radius – distance from centre to outside of a circle

• Diameter – distance from one side of the circle to the other, passing through the centre

Circles

6cm 6cm12cm

Diameter = 2 x radius

Radius = diameter ÷ 2

Circles

• Circumference – the distance around the outside of a circle.

• You are going to investigate the relationship between the circumference and the diameter.

Circles

1) Measure the circumference and diameter of the objects and record them in the table.

2) Divide the circumference by the diameter. Write your results in the table

3) Can you spot the common link?

Object Circumference Diameter C ÷ d

Starter

12cm

6cm 7cm

5cm 7cm

11cm

13cm

6cm15cm

18cm

4cm

Calculate the area of each of the following shapes.

Circles

Learning Objectives:

• Able to calculate the radius and diameter of a circle• Able to use a calculator to find the

circumference of a circle• Able to calculate the area of a circle

09/04/2023Grade D/C

Circles

• This relationship between the circumference and diameter is called ‘pi’

• The symbol for pi is ∏

• ∏ = 3.1415926….

• We often use 3.14 as an approximation

• It is found on calculators

Circles

• Circumference = ∏ x diameter

OR

• Circumference = 2 x ∏ x radius

Circles

4cm

Circumference = 2∏r

C = 2 x ∏ x 4

C = 8 x ∏

C = 25.13cm (2dp)

Circles

7cm

Find the circumference of the circle.

C = 2 x ∏ x 7

C = 14 x ∏

C = 43.98cm (2dp)

Starter

• Calculate the area of this trapezium

• Calculate the circumference of this circle4cm

8cm11cm

10cm

6cm

9cm

Circumference

Learning Objectives:

• Able to calculate the radius and diameter of a circle• Able to use a calculator to find the

circumference of a circle• Able to calculate the area of a circle

09/04/2023Grade D/C

CirclesIf I want to find the circumference of these circles, which formula should I use?

6cm

14cm

C = 2 x ∏ x rC = 2 x ∏ x 6C = 12 x ∏

C = 37.7cm (1dp)

C = ∏ x dC = ∏ x 14

C = 43.98 (2dp)

Circles

• Page– Exercise– Questions

Starter

• On your whiteboard, calculate the circumference of the following shapes.

9cm

6cm

10cm

Area of Circles

Learning Objectives:

• Able to calculate the circumference of a circle

• Able to calculate the area of a circle given the radius

• Able to calculate the area of a circle given the diameter

09/04/2023Grade C

Area of Circles

• Area = ∏ x radius2

• Area = ∏r2

radius

Area of Circles

• Area = ∏r2

• Area = ∏ x 42

• Area = ∏ x 4 x 4

• Area = 16 x ∏

• Area = 50.27cm2

4cm

Areas of Circles

7cm

Area of Circles

• Radius = 18 ÷ 2 = 9cm

• Area = ∏ x 92

• Area = 81 x ∏

• Area = 254.47cm2

18cm

Area of Circles

12cm

Your turn…

• Page 364 – 366– Exercise 16C– Questions 1, 3, 5, 6, 7*, 9*