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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	Space, Build understanding, Apply understanding
Topics	Angles and geometric reasoning
AC: Mathematics (V9.0) content descriptions	AC9M9M03 Solve spatial problems, applying angle properties, scale, similarity, Pythagoras' theorem and trigonometry in right-angled triangles
Numeracy progression	Understanding geometric properties (P7) Understanding units of measurement (P10) Proportional thinking (P7)
Copyright details
Organisation	reSolve Maths by Inquiry
Copyright	© Australian Government Department of Education, Skills and Employment 2021. Creative Commons BY-NC-SA 4.0.