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

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 ...

Video

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

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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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reSolve: Pythagoras' Theorem - Phone finding

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Downloadable

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Downloadable

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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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A Little Atmosphere

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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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What are pixels?

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Using maths to understand the universe

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Indigo Interior

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reSolve: Rectilinear Polygons

In this sequence of three lessons, students use geometric reasoning to establish relationships between angles in polygons and go on to make generalisations using algebraic expressions. Students explore and enumerate right angles in a series of rectilinear polygons and generalise their findings. They then explore the number ...

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In a spin

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reSolve: Gradient and Tangent

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Interactive

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This is a five-page HTML resource about solving problems concerning surface areas of prisms. It contains one video and five questions, two of which are interactive. The resource discusses and explains solving problems involving determining surface areas of prisms to reinforce students' understanding.

Video

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 ...