Lesson Notes By Weeks and Term v4 - JHS 1

Measurement

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Subject: Mathematics

Class: JHS 1

Term: 3rd Term

Week: 2

Grade code: B7.3.2.2.1

Strand code: 3

Sub-strand code: 2

Content standard code: B7.3.2.1

Indicator code: B7.3.2.2.1

Theme: GEOMETRY AND MEASUREMENT

Subtheme: Measurement

Lesson Video

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Performance objectives

Lesson summary

This lesson introduces learners to the concept of the area of a triangle. Instead of just memorizing a formula, learners will actively discover *why* the formula works by relating triangles to shapes they already know: rectangles and parallelograms. This skill is crucial not only for future mathematics but also for practical, everyday life in Ghana, from farming on a triangular plot of land to designing patterns in Kente cloth or building a roof for a house. Teaching and Learning Materials (TLMs): A4 paper or old exercise book pages for each learner/group Scissors for each group Rulers Pencils and pens Marker board and markers

Lesson notes

Part 1: Recap of Prior Knowledge (10 mins)

Before we learn about triangles, let's remember what we know about rectangles. Area: The amount of space a flat shape covers. We measure it in square units (e.g., cm², m²). Area of a Rectangle: We find this by multiplying its length by its width. Formula: `Area = Length × Width`

*Example:* A rectangular book cover is 10 cm long and 7 cm wide. Its area is 10 cm × 7 cm = 70 cm². Area of a Parallelogram: This is similar. We multiply its base by its perpendicular height. Formula: `Area = Base × Height`

*Note:* The perpendicular height is the straight-line distance from the base to the opposite side, meeting the base at a right angle (90°). It is NOT the slanted side. Part 2: The Discovery Activity - Deriving the Formula (25 mins)

Evaluation guide