AC9M7SP01 • Homework
Representing 3D Objects in 2D
Use nets, aerial/plan views, isometric and perspective drawings, and orthographic views. Explain why a representation is suitable as well as what it shows.
Part A — Short response
- Define a net and give one object that can be constructed from a net. (2)
- State the faces needed in a triangular prism net. (2)
- What information does an aerial or plan view show particularly well, and what important dimension can it hide? (2)
- Give one advantage of an isometric drawing and one limitation of a perspective drawing. (2)
- Which two dimensions are normally visible in a front orthographic view? (2)
Part B — Extended response
- A packaging designer is making a triangular-prism box. Describe a valid net, explain how you would test it, and give one advantage and one disadvantage of using the net as the representation. (5)
- A simple house has a rectangular body and a pitched roof. Explain how an aerial view and a front view communicate different information, and name simple prisms that could approximate the structure. (5)
- Compare isometric, perspective and orthographic drawings. For each, state a useful purpose, then choose the best representation for a builder who needs exact dimensions and justify your choice. (5)
- A block object has the same front view as another object but a different top view. Explain how this is possible and why multiple orthographic views reduce ambiguity. (5)
- Explain how you would respectfully investigate a First Nations Australian artwork or cultural map of Country/Place as a two-dimensional representation. Include why you should not assume that symbols or mapping conventions have universal meanings. (5)
Part C — Enrichment
11. Representation challenge. Design a small structure made from at least two simple prisms. Produce or describe (a) a top/plan view, (b) a front view, and (c) an isometric or perspective view. Explain what each representation communicates well, what it hides, and which combination you would give to a builder. Justify your choices.
Answers / checking guide
1
A net is a 2D arrangement of faces that folds to make a 3D object; examples include a cube, rectangular prism, triangular prism or pyramid.
2
Two congruent triangles and three rectangles.
3
It shows footprint/layout well; height is usually hidden or unclear.
4
Example: isometric shows several faces and overall 3D form at once. Perspective can foreshorten lengths, so apparent lengths are not automatically true measurements.
5
Width and height.
6
A valid net has 2 triangles and 3 rectangles arranged to fold without overlap. Test by paper folding or a fold simulation. Advantage: all faces are visible for fabrication/surface planning. Limitation: assembled depth/orientation is harder to visualise.
7
The aerial view shows footprint/layout but little height; the front view shows width, height and roof profile but not full depth. A rectangular prism can approximate the body and a triangular prism the roof.
8
Isometric: useful 3D form, parallel axes; perspective: realistic depth but poor for direct measurement; orthographic: clear face-on dimensions but requires multiple views. Dimensioned orthographic views are strongest for construction.
9
A single front projection can hide depth or arrangement. The top view reveals horizontal placement/depth, while side views add further constraints; together the views reduce ambiguity.
10
Use reliable source/community context, describe the spatial or relational information actually supported, and avoid assigning universal meanings to symbols or assuming Western scale-map conventions.
11
Responses vary. Full-credit work should use internally consistent views, identify what each view preserves/omits, and justify a useful combination such as plan + elevations for dimensions with isometric/perspective for visualisation.