Mathematics / Year 9 / Measurement and Geometry / Geometric reasoning

Curriculum content descriptions

Solve problems using ratio and scale factors in similar figures (ACMMG221)

Elaborations
  • establishing the relationship between areas of similar figures and the ratio of corresponding sides (scale factor)
General capabilities
  • Literacy Literacy
  • Numeracy Numeracy
  • Critical and creative thinking Critical and creative thinking
ScOT terms

Ratios,  Scale (Proportions),  Similarity (Geometry)

Video

MathXplosion, Ep 50: How to use a tetrahedron to solve the tree problem

How can you place four trees exactly the same distance apart from one other? By making a model! By using miniature trees to make a model of the problem, it becomes clear that a 2D solution is impossible. We learn how objects can help us visualise the problem situation, which in this case requires a 3D solution: a tetrahedron.

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Digital tectonics

This set of learning activities challenges students to use accessible digital technologies and hands-on engineering to measure simulated seismic vibrations, analyse and present data, and determine criteria for the design of earthquake tolerant buildings. The module includes a comprehensive teacher guide, curriculum links, ...

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Amp up the volume

This set of learning activities challenges students to build a portable amplifier that passively amplifies the sound produced by a smartphone. The module includes a comprehensive teacher guide, curriculum links, materials lists, design process guides and printable student resource sheets. The resource also provides an editable ...

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Moving out of home

This lesson explores costs and responsibilities associated with moving out of home and setting up living arrangements. The resource is part of a suite of lesson plans and activities from MoneySmart, designed to bring everyday financial topics into the classroom.

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Proportion, Graphs and Equations - Calculate

This unit challenges students to identify and describe everyday examples of ‘direct’ and ‘indirect’ proportion. They learn to recognise direct and inverse proportion from graphs, distinguish between positive and negative gradients and use the equation y = kx to model direct linear proportion.

Downloadable

Introduction to trigonometry

These lesson plans guide the teacher on how to introduce trigonometry to students through an investigation of similar triangles.

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Work sample Year 9 Mathematics: Similar triangles

This work sample demonstrates evidence of student learning in relation to aspects of the achievement standards for Year 9 Mathematics. The primary purpose for the work sample is to demonstrate the standard, so the focus is on what is evident in the sample not how it was created. The sample is an authentic representation ...

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Mathematics of bushfire

In these classroom activities students will be introduced to some of the basic mathematical principles that underpin wildfire science, with an emphasis on how theoretical concepts are used to aid our understanding of the real world, and bushfire in particular. They will learn about the complexities of the fire management ...

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A Little Atmosphere

This activity invites students to model the scaled thickness of the atmosphere on a globe using sheets of transparency material. The activity includes a list of tools and materials required, what to do and notice, an explanation for the underlying science of what students observe and suggestions for further activities.

Downloadable

Different ways to pay

This lesson challenges students to explore the pros and cons of various payment options, how they spend their money, different consumer products and where to go for more information about saving money and debt. During the lesson, students investigate multiple payment options to choose those that suit their circumstances, ...

Downloadable

The cost of cars

This lesson is designed for students to learn about car ownership in Australia and the real costs of buying and running a car. Students explore car ownership statistics in Australia, investigate the range of decisions people make about transport, calculate and compare costs of transport and make decisions on additional ...

Video

Mystery man Pythagoras meets his match

What do you know about Pythagoras? Join Vi Hart as she not only explains his theorem but raises some legends about his dark past! Follow Vi's timeline of famous mathematicians to find out in which century Pythagoras lived. See how Vi shows a proof of his theorem and raises what was a big dilemma for Pythagoras: the irrational ...

Interactive

Laptop wrap: Talking trigonometry

In this laptop-friendly resource, students consolidate their understanding of trigonometry by investigating practical applications of the ratios, highlighting the process they used to find a solution.

Interactive

The geometer's warehouse

This web-based, multimedia resource focuses on the geometry of the Stage 4 and Stage 5 Mathematics syllabus. It comprises 70 dynamic html worksheets, each exploring a different outcome in Stage 4 and Stage 5 geometry.

Interactive

Laptop wrap: Geometry gems

A page with a focus on using GeoGebra to enhance student understanding of various geometric properties and the importance of reasoning in proof. A laptop-friendly resource that includes supporting activities and links to resources.

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TIMES Module 33: Number and Algebra: factorisation - teacher guide

This is a 17-page guide for teachers. It continues the discussion of factorisation. In particular, the techniques for the factorisation of quadratic expressions are presented.

Interactive

Algebra four

This is an interactive game for two students in which they solve algebraic equations, similar to 'Connect four'. The players can choose from problems that are one- or two-step, quadratic, have distributive properties or have variables on both sides, and more than one problem type can be chosen. The length of time each player ...

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TIMES Module 22: Measurement and Geometry: scale drawings and similarity - teacher guide

This is a 41-page guide for teachers. It contains an introduction to scale drawings and similarity, and in particular the tests for triangles to be considered similar. Applications of similarity are included throughout the module.

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TIMES Module 11: Measurement and Geometry: area, volume and surface area - teacher guide

This is a 15-page guide for teachers containing explanations of the derivation of formulas for the areas of parallelograms, trapeziums, rhombuses and kites. Formulas for the volumes and surface areas of prisms and cylinders are obtained. Applications of these formulas are given. A history of the development of these concepts ...

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TIMES Module 22: Number and Algebra: consumer arithmetic - teacher guide

This is a 23-page guide for teachers, providing an introduction to the financial mathematics component of the number and algebra strands for years 9 and 10. A brief history of the concept of money concludes the module.