Activity Introduction

Quick summary: Students will investigate the production and recycling of aluminium using deodorant cans as a context. They will investigate the costs of manufacturing aluminium from raw materials and compare these to recycling figures. Students will identify relationships showing direct proportion and use relevant formulas to calculate values related to aluminium production and carbon emissions. 

This activity has been developed in partnership with Visy. For over 70 years Visy has been committed to finding sustainable solutions for Australia’s recyclables and helping to reduce local landfills. Visy collects, receives and sorts paper, cardboard, glass, plastics, steel and aluminium from households, businesses and schools with the purpose of reusing these products in the re-manufacture of new packaging products.

Learning intentions:

  • Students will understand the impact of recycling aluminium
  • Students will be able to recognise directly proportional quantities
  • Students will able to apply direct proportion formulas to solve problems related to the production of aluminium from raw and recycled materials.

21st century skills:

Critical ThinkingGlobal CitizenshipSocial SkillsProblem Solving

Australian Curriculum Mapping

Content descriptions:

Year 9 Maths

  • Solve problems involving direct proportion. Explore the relationship between graphs and equations corresponding to simple rate problems (ACMNA208).

General capabilities: Numeracy, Critical and creative thinking, Ethical understanding.

Cross-curriculum priority: Sustainability OI.8.

Relevant parts of Year 9 Mathematics achievement standards: Students interpret ratio and scale factors in similar figures.

Topic: Recycling, Sustainability.

Unit of work: Visy Education – Secondary Mathematics.

Time required: 70 mins.

Level of teacher scaffolding: Medium – teachers will need to guide students through various parts of this lesson, particularly the introduction, to ensure students understand the background knowledge.

Resources required:

Keywords: Recycling, aluminium, aerosol cans, rate, ratio, direct proportion, deodorant cans.

The information and statistics included in this document are approximate and have been simplified for educational/illustrative purposes. They should not be relied upon for any other purpose.

Cool Australia’s curriculum team continually reviews and refines our resources to be in line with changes to the Australian Curriculum.


Teacher Worksheet

Teacher Preparation

Learning intentions: Students will...

  • ... understand the impact of recycling aluminium
  • ... recognise directly proportional quantities
  • ... be able to apply direct proportion formulas to solve problems related to the production of aluminium from raw and recycled materials.

Success criteria: Students can...

  • ... recall proper recycling methods for metals
  • ... recognise proportional relationships
  • ... solve for the proportionality constant, k, using formulas and aluminium production values
  • ... calculate the bauxite requirements and carbon emissions using direct proportion formulas.

Teacher content information: What do you do with the things you no longer want or need, such as the packaging from the food you buy or bottles you drink from? Many of us have grown up thinking of this as 'waste', as something we need to just get rid of. But what if we think of these materials as a resource for creating new and useful products? What if we can re-imagine

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Student Worksheet

Thought starter: Deodorant cans - Where do they come from and where do they go?

Part A: Introduction – Where does my deodorant can come from?

1. Your deodorant can is made from metal, but what kind of metal? Do you know? Or can you guess? Record your ideas below.

2. Have a look at the Visy Raw Materials Chart and use this to to state what deodorant cans are actually made of, and what raw materials are used to produce these metals.

3. Read through the following sections of the Aluminium Factsheet: “How is aluminium made?” and “How much energy does it cost?”. As you are reading, identify four directly proportional relationships and calculate the constant of proportionality, k, for each.

Table 1. Proportional relationships

Directly proportional relationship
y ∝ x
Proportionality constant
Using y = k x
Hint: The input values for each relationship should be y, and the output values should be x.


k = 



k =



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