Lesson Notes By Weeks and Term v4 - JHS 3
COMMUNICATING DESIGNS
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COMMUNICATING DESIGNS
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Subject: Career Technology
Class: JHS 3
Term: 3rd Term
Week: 1
Grade code: B9.5.1.2.1
Strand code: 5
Sub-strand code: 1
Content standard code: B9.3.3.1
Indicator code: B9.5.1.2.1
Theme: DESIGNING AND MAKING OF ARTEFACTS/PRODUCTS
Subtheme: COMMUNICATING DESIGNS
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Welcome, learners! In our journey through Career Technology, we have seen many beautiful and useful products, from the chairs we sit on to the houses we live in. But how does the carpenter know exactly how to build the chair? How does the architect tell the builder exactly how the house should look from all sides? They use a special type of drawing to communicate their ideas clearly. This method is called Orthographic Projection. Understanding orthographic projection is a master key that unlocks the world of design, engineering, and manufacturing.
a. What is Projection?
Imagine you are in a dark room with a single torch. You hold up a mango, and the torch casts a shadow of the mango on the wall. That shadow is a projection of the mango. It's a 2D representation of a 3D object.
However, this shadow changes shape depending on the angle of the torch. Technical drawing needs a more precise method. b. What is Orthographic Projection?
The word "ortho" comes from a Greek word meaning "right" or "straight," and "graphic" means "drawing." So, orthographic projection is a way of drawing a 3D object in 2D by looking at it from "straight on" or at a right angle (90°).