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What is similarity?

The first of a series of lessons that explores the meaning of similarity and how a shape can be translated to prove they are similar. The following lessons demonstrate the shortcuts and rules for testing and proving similarity of plane shapes.

Additional details

Year level(s) Year 9
Audience Teacher
Purpose Content knowledge, Teaching resource, Student task
Format Web page
Teaching strategies and pedagogical approaches Explicit teaching
Keywords Transformation, Ratio, Triangle, Angle, Proof, Congruent, Similar, Scale factor, Enlargement

Curriculum alignment

Curriculum connections Critical and creative thinking, Numeracy
Strand and focus Space
Topics Angles and geometric reasoning
AC: Mathematics (V9.0) content descriptions

Solve spatial problems, applying angle properties, scale, similarity, Pythagoras' theorem and trigonometry in right-angled triangles

Numeracy progression Understanding geometric properties (P7)
Proportional thinking (P7)
Understanding units of measurement (P10)

Copyright details


Illustrative Mathematics


© Open Up Resources/Illustrative Mathematics. Creative Commons BY 4.0.