TERM – 3^{RD} TERM
WEEK ELEVEN
Class: Junior Secondary School 3
Age: 14 years
Duration: 40 minutes of 5 periods each
Date:
Subject: BASIC TECHNOLOGY
Topic: SCALE AND SCALE DRAWING
SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to
INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers,
demonstration, videos from source
INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures, mathematical sets, drawing instruments
INSTRUCTIONAL PROCEDURES
PERIOD 1-2
PRESENTATION |
TEACHER’S ACTIVITY |
STUDENT’S ACTIVITY |
STEP 1 INTRODUCTION |
The teacher explains scale and scale drawing to the students. |
Students pay attention |
STEP 2 EXPLANATION |
Teacher discusses the types of scale drawing Teacher explain the procedure for carrying out scale drawing. |
Students pay attention and participate |
STEP 3 DEMONSTRATION |
Teacher guide students to carry out simple scale drawings. |
Students pay attention and participate |
STEP 4 NOTE TAKING |
The teacher writes a summarized note on the board |
The students copy the note in their books |
NOTE
SCALE AND SCALE DRAWING
A scale drawing is an enlargement of an object. An enlargement changes the size of an object by multiplying each of the lengths by a scale factor to make it larger or smaller. The scale of a drawing is usually stated as a ratio.
The scale represents the rate of enlargement or reduction from the original object.
Types of scale
Scaled Drawing
Scale: The scale is the relation between the actual measurements of an object and the measurements of a drawn object. For example, if a rectangular garden is drawn on a blueprint with a scale of 1 unit = 1 foot, that means every 1 unit of the drawing represents 1 foot of the garden in real life.
Procedure for Scale Drawing
6 units x 2/1 = 12 cm
12 cm x 1/3 = 4 units
Example: The drawing below has a scale of 1 unit = 10 ft. Reproduce the drawing with a scale of 1 unit = 5 ft.
Solution.
Procedure
Side AB: 5 units x 10/1 ft = 50 ft
Side AC: 12 units x 10/1 ft = 120 ft
Side A'B':
50 ft x 1unit/ 12cm = 10 units
Side A'C':
120 ft x 1 unit/12 cm = 24 units
3.Then, draw a new scaled drawing using the new scaled measurements.
Triangle A
EVALUATION: 1. The drawing below has a scale of 1 unit = 2 cm. Reproduce the drawing with a scale of 1 unit = 6 cm.
Rectangle ABCD. Side AD is 6 units and side DC is 9 units.
CLASSWORK: As in evaluation
CONCLUSION: The teacher commends the students positively