Lesson Overview

Students extend their CAD capability with symmetry, mirror, fillet, assembly and sketch constraints. They first build a "cube within a cube" model, then explore how CAD assemblies show fit and movement, and finally learn how constraints make sketches behave predictably.

Learning Objectives

By the end of this lesson, students will be able to:

1
Use the top plane and origin to centre geometry for symmetrical modelling
2
Apply Mirror to duplicate 3D bodies across a plane
3
Use Fillet to round edges and explain why rounded edges matter for safety, durability, manufacturing and appearance
4
Build a simple assembly and test motion using a revolute relationship
5
Explain under-constrained, constrained and over-constrained sketch states
6
Apply coincident and concentric-style constraints to lock sketch geometry predictably

Singapore Curriculum Alignment

MOE Design & Technology: modelling accuracy, parts and assemblies, communication of design intent. ALP / maker learning: iterative improvement and testing movement or fit digitally before fabrication.

Prior Knowledge Required

Confidence with basic sketch, extrude and viewing tools in Onshape
Basic concept of dimensioning, origin points and planes

Materials & Resources

Item	Quantity
Laptop or desktop computer with internet access	1 per student or pair
Onshape account	Required
Mouse	Recommended
Teacher demonstration screen / projector	1

Safety Notes

Maintain safe workstation habits during extended computer use
Encourage students to save versions before major modelling changes
If physical printed samples are shown, remind students to handle them carefully