THEME – MEASUREMENTS AND GEOMETRY
PREVIOUS LESSON – Second Term Scheme of Work and Plan Lesson Notes for MATHEMATICS Week 1 to Week 12 Primary Schools
TOPIC – AREA OF RIGHT – ANGEL TRIANGLES
By the end of the lesson, the pupils should have attained the following objectives (cognitive, affective and psychomotor) and should be able to calculate the area of a right angled triangle.
The teacher will teach the lesson with the aid of cuboid, rectangle and triangle.
METHOD OF TEACHING – Choose a suitable and appropriate methods for the lessons.
Note – Irrespective of choosing methods of teaching, always introduce an activities that will arouse pupil’s interest or lead them to the lessons.
1. Scheme of Work
2. 9 – Years Basic Education Curriculum
3. Course Book
4. All Relevant Material
5. Online Information
CONTENT OF THE LESSON
LESSON ONE – INTRODUCTION
Pupil’s Activities 1 – Properties of Cuboid
Teacher’s Activities – Questions
1. The objects below is called ______________.
2. What shape does represent in mathematics?
3. How many faces does the objects has?
4. Many corners or vertices does it have?
5. The object is used for ______________.
6. Mention 5 objects that can be packaged inside.
Note – Guides or leads the pupils where necessary.
1. Carton or box
3. Six (6) faces
4. Eight vertices (corners)
6. Indomie, wine, milk, television, radio, Maclean, chalk, marker, etc.
Teacher’s/Pupil’s Activities 2 – Introduction to Rectangle
Teacher’s Activities – Cut one of the faces of the carton. Asks pupils to draw and name it.
Pupil’s Response – R ectangle
Pupil’s Activities 3 – Lengths of Rectangle
1. Measure each length of the rectangle.
2. Compare each length with another.
3. Use measurements to describe what rectangle means.
4. Mention 5 objects with rectangular face or shape.
1. 10 cm, 7 cm, 10 cm and 7cm.
2. Two of the lengths are equal to each other.
3. Rectangle is a shape with 4 length. Two of its lengths are equal to another.
4. Board, sheet of paper, door, wall or floor, top of desk, etc.
Teacher’s remark – A rectangle is a 4 sided with opposite parallel lengths are equal length. It is one of the group called quadrilateral.
LESSON TWO – RECTANGLE AND TRIANGLE
Pupil’s Activities 1 – Measure the Lengths of Rectangle
Teacher’s remark – The length and Breadth of rectangle are 7 cm and 3 cm.
Pupil’s Activities 2 – Area of Rectangle
Find the area of rectangle in activities 1 by multiplying length by Breadth.
Area = Length x Breadth
= 7 cm x 3 cm
= 21 cm²
Pupil’s Activities 3 – Cutting Out A Right Angle Triangle
1. Draw a diagonal and cut out the rectangle.
2. Then cut along the diagonal.
3. What shape did you cut out.
Teacher’s remark – Two right angles are made up of a rectangle.
Teacher’s/Pupil’s Activities 2 – Area of Triangles
Draw and find the area of a rectangle of length 8 cm and breadth 5 cm.
Area = 5 cm x 8 cm
= 40 cm²
Teacher’s question – If the area of the rectangle is 40 cm², what is the area of triangle if the rectangle is cut through the diagonal?
Expected pupil’s response – The area of triangle is half of the rectangle. That’s, 40 cm² ÷ 2 = 20 cm²
Pupil’s Activities 2 – Class Exercise/Take Home
Draw and find the area of rectangle whose
1. Length 12 cm and breadth 3 cm.
2. Length 15 cm and breadth 6 cm.
3. Length 4 cm and breadth 8 cm.
Then, find the area of triangle if the rectangle is cut through the diagonal.
LESSON THREE – AREA OF TRIANGLES (½ b x h)
Teacher’s/Pupil’s Activities 1 – Area of Triangles
Area of rectangle = Length x Breadth
= L x B
Area of Triangle = ½ x L x B
= ½ x B x H or ½bh
Where B stands for the base of the length and H is the breadth.
Pupil’s Activities 2 – Application of ½bh
Find the areas of the triangle below,
Area of Triangle = ½bh,
Where b = 8 cm and h = 6 cm
A = ½ x 8 cm x 6 cm
= 4 cm x 6 cm (8 cm ÷ 2 = 4 cm)
= 24 cm²
Pupil’s Activities 3 – Class Exercise/Take Home
Find the areas of triangles which have these sides,
1. Base is 4 cm and height is 5 cm.
2. Base is 12 m and height is 6 m.
LESSON FOUR – QUANTITATIVE REASONING
As stated in the quantitative book or textbook.
To deliver the lesson, the teacher adopts the following steps:
1. To introduce the lesson, the teacher revises the previous lesson. Based on this, he/she asks the pupils some questions;
2. Guides pupils to divide a rectangle into two halves along its diagonal to form two equal right angled triangles.
3. Guides pupils to derive the formula for area of right angled triangles i.e. 1⁄2 of area of rectangle of 1⁄2 (base × heights).
4. Guides pupils to calculate the area of the right angled triangle.
Pupil’s Activities – Derive and use formula to calculate the area of a right angled triangle.
To conclude the lesson for the week, the teacher revises the entire lesson and links it to the following week’s lesson.
Pupils to find the area of a given right angled triangle.