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reSolve: Mechanical Linkages: Similar Triangles

This sequence of lessons explores the geometry of similar triangles using two real-world objects: ironing boards and pantographs. In the first lesson, students investigate different ironing board leg lengths and pivot positions using similar and congruent triangles. In the second lesson, they use their knowledge of parallelogram properties and similar triangles to explore and explain how pantographs work. Each lesson is outlined in detail including curriculum links, materials needed, sample answers, discussion points and student resources such as links for simulations online. This sequence is part of the reSolve: Maths by Inquiry special topic 'Mechanical linkages and deductive geometry'.

Additional details

Year level(s) Year 9
Audience Teacher
Purpose Teaching resource
Format Downloadable resources
Teaching strategies and pedagogical approaches Mathematics investigation
Keywords triangles (shapes), dilation, similarity (geometry), explicit teaching

Curriculum alignment

Curriculum connections Numeracy
Strand and focus Geometry, Build understanding, Apply understanding
Topics Angles and geometric reasoning
AC: Mathematics content descriptions
ACMMG220 Use the enlargement transformation to explain similarity and develop the conditions for triangles to be similar
National numeracy learning progression Understanding geometric properties - UGP5

Copyright details


reSolve Maths by Inquiry


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