# Measures: scaling down

TLF ID L2311

Compare the areas of squares, rectangles and triangles before and after being scaled down (reduced). Notice that 'similar shapes' in the mathematical sense have the same shape but different areas. Explore the relationship between side-length reduction and area reduction when scaling down shapes. This learning object is the third in a series of eight objects that progressively increase in difficulty.

#### Educational details

Key learning objectives
• Students manipulate shapes to distinguish between similar and non-similar plane shapes.
• Students apply a formula to calculate the area of a range of shapes.
• Students identify the relationship between side length and area in similar shapes.
Educational value
• Demonstrates the relationship between side length and area in similar shapes.
• Illustrates the meaning of similarity in plane shapes.
• Features a range of scalable plane shapes with side lengths displayed in whole numbers.
• Provides opportunities to use multiplication facts in ratio and scale situations.
• Includes tables to help students record the relationship between side length and area in similar plane shapes.
• Encourages students to recognise number patterns and make a general rule based on a series of observations.
Year level

9

Learning area
• mathematics
Strand
• Mathematics/Measurement and geometry
Concept
• Mathematics/Plane geometry
• Mathematics/Generalisations
• Mathematics/Shape perception
• Mathematics/Ratio and proportion
• Mathematics/Size and shape
• Mathematics/Transformations
• Mathematics/Scale
• Mathematics/Scaling
Skill
• Analysis;
• Application;
• Comprehension;
• Knowledge
Student activity
• Interactives;
• Experiment;
• Analysis;
• Modelling
Learning design
• Experiential learning;
• Independent learning;
• Problem solving;
• Visual learning

#### Other details

Contributors
• Technical implementer
• Script writer
• Name: Rod Rees
• Organisation: Rees Films Pty Ltd
• Address: Blackburn VIC 3130 Australia
• Subject matter expert
• Name: Howard Reeves
• Address: Lindisfarne TAS 7015 Australia
• Educational validator
• Publisher
• Date of contribution: 20 Sep 2013
• Organisation: Education Services Australia
• Address: Melbourne VIC 3000 Australia
• URL: http://www.esa.edu.au/
Access profile
• Colour independence
• Device independence
• Hearing independence
Learning resource type
• Interactive Resource
Browsers
• Microsoft Internet Explorer - minimum version: 8.0 (MS-Windows) - maximum version: 9.0 (MS-Windows)
• Firefox - minimum version: (MS-Windows)
• Safari - minimum version: 5.1 (MacOS)
Operating systems
• MacOS - minimum version: 10.6
• MS-Windows - minimum version: XP - maximum version: 7
Rights
• © Education Services Australia Ltd, 2013, except where indicated under Acknowledgements.