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)

Online

reSolve: Pythagoras' Theorem - Phone finding

This lesson challenges students to apply Pythagoras' Theorem to explore a practical real-world problem. Students explore technology reliant on mathematical concepts. The lesson is outlined in detail including curriculum links, vocabulary, materials needed, sample answers, discussion points and student resources such as ...

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 ...

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, ...

Text

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.

Online

Pythagoras and trigonometry (Measurement): Year 9 – planning tool

This planning resource for Year 9 is for the topic of Pythagoras and trigonometry. Students apply and build upon knowledge of Pythagoras’ theorem, angle properties, trigonometry and scales to solve problems involving right-angled triangles.

Online

Mathematical modelling (Measurement): Year 9 – planning tool

This planning resource for Year 9 is for the topic of Mathematical modelling. Students continue to solve mathematical problems from the real world around them. They draw upon knowledge learnt in the area of Measurement.

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.

Video

Modelling climate changes

There is a saying: 'climate is what you expect and weather is what you get'. |Understanding climate change is very difficult for most people, especially when the weather we experience is different from the information we are given by scientists about the climate changing. The difference is that weather reflects short-term ...

Online

reSolve: Tree Biomass

In this sequence of two lessons, students investigate how many trees would be required to supply paper for their school for a year. Students use similar triangles, Pythagoras' Theorem and algebra to design and construct a Biltmore stick, used to measure the diameter and height of a tree. They measure trees, calculate their ...

Text

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 ...

Video

MathXplosion, Ep 33: On the grid

Explore graphs, grids and mapping with a focus on reading and writing location data using coordinate geometry. Grids and maps illustrate the concepts of parallel/perpendicular lines (axes or labelled number lines), ordered pairs and intersection points.

Video

How does income tax work?

Gen Fricker makes income tax interesting! Learn about income tax - what it is, how it works and when you have to pay it. Easy-peasy! Then test yourself with ASIC Moneysmart's "Things to think about" classroom exercises.

Video

My Five Cents: Why investing can be risky

Planning to get rich quick by investing one day? Before you jump in, let Gen Fricker explain some of the risks involved with different types of investments. Then test yourself with ASIC MoneySmart's "Things to think about" classroom exercises.  

Video

My Five Cents: What is compound interest?

Compound interest will be one of the most important things you ever learn. Don't believe it? Gen Fricker will explain why. Learn how compound interest works, and why saving now can help you later. Game changer! Then test yourself with ASIC MoneySmart's "Things to think about" classroom exercises.

Text

Volume of a Pyramid and a Cone

This resource is a web page containing an investigative task to explore volume. Derive the formulae for the volumes of a square-based pyramid and a cone, using mathematical concepts. A printable resource is also available to support the task. This resource is an activity from the NRICH website.

Text

Indigo Interior

This resource is a web page containing a problem solving task that requires an understanding of Pythagoras' theorem. The task involves finding the area of shaded region with a circle with a known area. To solve the problem students need to establish a right angled triangle and apply Pythagoras' theorem. A printable resource ...

Online

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 ...

Online

Australia's Trade through Time

Using an interactive timeline created by the Department of Foreign Affairs and Trade, this Teacher guide provides 12 series of learning experiences that engage students in the analysis and interpretation of data about Australian trade from 1900 to the present day. Students study videos, tables, images and texts in order ...

Interactive

MoneySmart: MilbaDjunga - how can I start my own business?

The MilbaDjunga secondary unit 'How can I start my own business?' is an interactive online unit developed to support teachers of Aboriginal and Torres Strait Islander students to teach consumer and financial literacy. It leads students through a step-by-step process to start a small business and is accompanied by teacher ...

Online

Tax, Super + You

Tax, Super + You is designed to provide teachers and parents with practical resources to help students in Years 7-12 understand the value of tax and superannuation, and have confidence when entering the workforce. Registration for a free account is required to access the full suite of materials.