Communicating Designs · JHS3 Career Technology

Lesson notes

Learning Objectives

Indicator: B9.5.1.2.1 - Describe the principles of orthographic projections

By the end of the lesson, learners can:

Explain what orthographic projection is and why it is used to communicate designs in two dimensions.
Describe the key principles of first angle (British method) and third angle (American method) orthographic projections, including the positions of the plan, front view, and end view.
Sketch and label the standard symbols for first angle and third angle orthographic projections.
State at least three reasons why orthographic projections are important for producing artefacts and products.
Identify the differences between first angle and third angle projection arrangements using a physical mock-up or drawn example.

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Curriculum details

Strand: Designing and Making of Artefacts/products (Strand 5)
Sub-strand: Communicating Designs (5.1)
Content standard: B9.5.1.2 - Demonstrate understanding of orthographic projections
Indicator: B9.5.1.2.1 - Describe the principles of orthographic projections
Suggested placement: Term 2, Week 11 (Week 23 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: Career Technology, Common Core Programme (JHS1-JHS3), 2023, p. 105
Transcribed from the official NaCCA publication. Check this page against the source.

Exemplars (from the NaCCA curriculum)

1. Explain what is meant by orthographic projection.
E.g. Drawing the three views of objects in two dimensions.
2. Discuss the principles of orthographic projections for both first and third angle orthographic projections.
E.g.
- For first angle (British method), the plan is projected below the front view
- For third angle (American method), the plan is projected above the front view.
Note: Use mock-ups to facilitate understanding
3.Sketch the symbols for first and third angle orthographic projections.
4. Discuss the importance of drawing orthographic projections of objects.
E.g., To get detailed dimensions of parts for production of artefacts/ products.