Days

W.A..L.T:

Content

Starter

Class activities

Plenary

Homework

**Monday**

**Meaning of circle and parts of a circle**

Resources

a cardboard with circle drawn on it

A circle is a perfect round plane.

Examples of circle are; coins, wheels, rings, tin tops and bottom of buckets.

Parts of a Circle.

Centre: the point at the middle of the circle.

Circumference: is the curved outer edge of the circle. (the distance round the circle ). It is the longest part of a circle.

Diameter: the line from a side through the centre to another side. It divides the circle to equal halves. Half of a diameter is a radius.

Radius: is any straight line drawn from the centre to the circumference.

Semi-circle: half of a circle.

Quadrant : is a quarter part of a circle.

Chord: a straight line joining two points on the circumference. ( a chord does not divide a circle into equal halves like the diameter)

Sector: is a region between two radii and the circumference.

Begin the lesson by drawing a circle on the board and asking them what shape it is.

Pupils should be able to mention at least 4 parts of a circle then give explanation on them.

**Tuesday**

**Finding the Area of circle**

The area of a circle is found by using the formula Ï€r² , where Ï€ is pi with value as 22/ 7 or 3.142 and where r is the radius of the circle.

Example:

1. Find the area of the circle with radius 7cm. Take Ï€ a 22/7

Solution

Area = Ï€r² = Ï€ X r X r

= ( 22/7 X 7 X 7 ) cm²

= 154cm²

2. Find the area of a circle of diameter 7cm. Take pi as 22/7

solution

radius is half of a diameter 7/2cm = 3 cm

area = Ï€r² = Ï€ X r X r

= ( 22/7 X 3.5 X 3. 5) cm²

= 38.5 cm²

Start the lesson by stating the formula for finding the area of the circle

Pupils should be able to calculate the area of the shaded portion of the shape given

**Wednesday**

**Finding the radius of a circle.**

If you are required to find the radius of a circle when the area and pi are given, the rule is ; change the formula for finding the area.

Area = Ï€r² ( divide both sides by Ï€ )

A = Ï€r²

Radius = (A/Ï€)¹/² (square root both sides)

Example : find the radius of a circle whose area is 154 cm2 . takes Ï€ as 22/7

Radius = (A/Ï€)¹/²

Radius = (154/3.142)¹/²

= 7cm²

Begin the lesson by doing the first example for them.

Pupils should be able to calculate the area of the given shape correctly.

**Thursday**

**Finding the area of semi- circle**

Example : find the area of the semi - circle with radius 7cm.Take Ï€ as 22/7.

Solution :

Area of semi- circle = Ï€r²/2

= ( 22/7 X 7 X 7 )/2 cm²

=19.25 cm²

Begin the lesson by doing the first example for them.

Pupils should be able to calculate the area of the given shape correctly.

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