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Mathematics / Year 8 / Measurement and Geometry / Geometric reasoning

View on Australian Curriculum website Australian Curriculum, Assessment and Reporting Authority
Curriculum content descriptions

Establish properties of quadrilaterals using congruent triangles and angle properties, and solve related numerical problems using reasoning (ACMMG202)

  • establishing the properties of squares, rectangles, parallelograms, rhombuses, trapeziums and kites
  • identifying properties related to side lengths, parallel sides, angles, diagonals and symmetry
General capabilities
  • Literacy Literacy
  • Numeracy Numeracy
  • Critical and creative thinking Critical and creative thinking
ScOT terms

Angles,  Congruence (Geometry),  Quadrilaterals

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Year level 7-8
Resource type
Learning area Mathematics
Teacher resource

reSolve: Polygon Pieces

This lesson explores the geometry of cutting polygons in different ways and using algebra to express subsequent findings. Students use one straight cut to divide a convex polygon into two new polygons. They make generalisations about the total number of sides of the two new polygons, and about the number of different combinations ...

Interactive Resource

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 Resource

The Mathematical Toolkit

A 2D Shapes tool that can be used to create geometric objects such as quadrilaterals, circles, triangles, lines, arcs, rays, segments and vectors on a coordinate grid. Plot and label the vertices to reveal the internal angles, side lengths, area and perimeter, then manipulate the shapes on a grid to transform their shape ...

Teacher resource

reSolve: Mechanical Linkages: Quadrilaterals

This series of six lessons explores geometry using real world contexts focussed on the dynamics of linkages and moving joints of everyday tools and objects. Students use physical models and computer simulations, the lessons move from a view of geometry as a study static diagrams to encompass movement. Each lesson is outlined ...


BBC Bitesize: 2-D shapes - revision

This is a collection of information sheets on the geometrical properties of special quadrilaterals and 2-D representations of 3-D shapes. Students have access to a multiple-choice test to assess their knowledge of quadrilaterals and representations of 3-D shapes. This resource is one of a series of online resources from ...

Teacher resource

reSolve: Quarter Cartons

This lesson challenges students to use algebra and proportional reasoning to investigate how changing the size of a paper square or rectangle impacts the dimensions of a box folded from that paper. Students apply knowledge about nets of 3D objects and explore algebraic relationships through a set of hands-on activities ...

Interactive Resource

Numeracy wrap: Parallelogram peculiarities

Interactive activities that guide students to investigate properties of parallelograms.

Interactive resource

Exploring quadrilaterals

Examine the sides and angles of a four-sided shape. Identify its geometric properties such as the number of sides of equal length. Classify the shape as a parallelogram, rhombus, square, rectangle, kite or trapezium. Notice that some quadrilaterals can be classified in different ways.

Interactive resource

Congruent triangles

Find out about congruent and non-congruent triangles and the conditions required to make them. Use line segments and angles to build two congruent triangles for three different combinations of sides and angles. Explore the SSS case (side, side, side), the SAS case (two sides and the included angle) and the ASA case (two ...


Geometric reasoning - congruence

This is a website designed for both teachers and students that introduces congruence of shapes in the plane through transformations. In particular, transformations, translations, reflections in an axis and rotations of multiples of 90 degrees are used to define congruence and to identify congruent shapes. The four congruence ...

Interactive resource

Exploring triangles

Find an active triangle in a photograph. Work out its angles by applying principles of opposite angles, complementary angles, supplementary angles and the sum of interior angles. Watch a video showing how triangles are used in buildings and other structures.

Interactive resource

Exploring trigonometry

Label the three sides of a right-angled triangle as hypotenuse, adjacent and opposite sides. Identify which sides form a trigonometric ratio such as cosine or tangent. Watch a video showing how trigonometry is used to help planes land safely.

Interactive resource

Exploring ratios and proportions

Explore ratios by comparing the dimensions of two rectangles. Choose a scale to enlarge the smaller shape and identify whether its sides are proportional to those of the larger rectangle. For example, a rectangle with sides in the ratio 4:5 has an equivalent ratio to a rectangle with sides in the ratio 12:15. Watch a video ...

Interactive Resource

Planes of Symmetry

An animated tutorial demonstrating planes of symmetry of solids. An interactive quiz is included.

Interactive Resource

Area of a parallelogram

This is a Geogebra activity used to teach the area of a parallelogram. Suitable for use with an interactive whiteboard (IWB).

Interactive Resource

Renovate, Calculate!

A student resource that explores the use of mathematics in the trades. Highly interactive investigations into ratio, areas of special quadrilaterals and right-angled trigonometry.

Interactive Resource

Numeracy wrap: Race across transversals

Interactive activities that guide students to explore angles in parallel lines.

Teacher resource

TIMES Module 14: Measurement and Geometry: congruence - teacher guide

This is a 30-page guide for teachers. It contains an introduction to congruence, in particular the congruence tests for triangles. Applications of congruence are included throughout the module.


BBC Bitesize: transformations - revision

This is a set of illustrated information sheets with a focus on congruence and transformations. Examples with answers are included and students have access to multiple-choice questions to assess their learning. This resource is one of a series of online resources from the BBC's Bitesize collection.

Teacher resource

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.