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: 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 ...

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 ...

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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.

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 ...

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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, ...

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 ...

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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.

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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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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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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.

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.

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Introduction to trigonometry

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

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Maths inside bees and beehives

Bees are necessary for assisting many plants to produce the food we eat, including meat and milk. Colony collapse disorder, which describes the disappearance of beehives, could have catastrophic effects on food production. Australian scientists are applying their maths and science knowledge to build up a picture of a healthy ...

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reSolve: Monte Carlo Simulations

This sequence of two lessons explores how statistical techniques that rely on randomly generated data can be used to solve problems. In the first lesson, students compare different methods for calculating the area of an irregular shape, using the context of oil spill maps. They are introduced to the Monte Carlo method for ...

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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.  

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My Five Cents: Why borrowing can cost you more

Think credit cards are basically free money? Gen Fricker will make you think again. Learn how interest rates and fees affect the money you borrow, and why they may be more expensive in the long run. Oh dear! Then test yourself with ASIC MoneySmart's "Things to think about" classroom exercises.  

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Catalyst: Nautical Robots

How might you find out how much and where the Earth's oceans are warming? Watch the report by Ruben Meerman and discover how more than 3000 'nautical robots', known as argo floats, have been placed in the oceans to collect data on variations in temperature, pressure and salinity.

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What are pixels?

Meet Kevin Systrom and Piper Hanson as they explain how digital images work. What are pixels, those tiny dots of light, made from? How are colours created and represented? What does Kevin say about the way mathematical functions are used to create different image filters. What is the difference between image resolution ...

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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.