Activity Introduction

Quick summary: Students use authentic data to answer problems about recycling. They calculate and use percentages to compare rates of recycling and environmental benefits. They do a quick survey and calculate percentages to help them to analyse their data.

This lesson has been developed as part of the Schools Recycle Right Challenge for Planet Ark’s National Recycling Week. Register your lesson or other activities so they can be counted towards the national achievement and to receive other free support materials.


Learning goals for this activity include: Calculate and apply percentages to data to help to analyse the data and answer mathematical questions. Demonstrate how mathematics is used to understand environmental issues.  

21st century skills: 

Communicating Critical Thinking   

Australian Curriculum Mapping

Year 7 Mathematics:

  • Find percentages of quantities and express one quantity as a percentage of another, with and without digital technologies (ACMNA158)
  • Connect fractions, decimals and percentages and carry out simple conversions (ACMNA157)

Time needed: 50 min

Level of teacher scaffolding: Medium – keep an eye out for those students who get confused about calculating percentages.

Resources needed: Scrap paper, access to a spreadsheet application that can produce pie graphs.

Digital technology opportunities: Convert a table of data into a pie graph using Excel

Assumed prior learning: Have had an introduction to percentages, have an understanding of ratios, familiar with a spreadsheet program.

Keywords: Percentage, ratio, weight, greenhouse gases, energy, recycling

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


These Planet Ark resources were developed by Cool Australia with funding from the Alcoa Foundation.


Teacher Worksheet

Teacher Preparation

Overarching learning goals: Calculate and apply percentages to analyse data and answer mathematical questions. Demonstrate how mathematics is used to understand environmental issues.  

Teacher content information: Aluminium is a metal that can be recycled again and again without being degraded. Recycling aluminium is important as it only takes 5% of the energy to recycle it compared with processing the raw material bauxite into aluminium. So for each can recycled there is a 95% energy saving.

The method for collecting aluminium cans will affect the percentage being recycled.

  1. People dropping off cans at a collection point to be recycled are likely to have the lowest rate. People have to make an extra effort to take their cans to the centre. Because the aluminium in the cans is valuable the cans can be sold by weight. A scrap metal dealer will pay about $1 per kg of cans. It takes about 67 cans to make 1kg. If a large amount of cans are involved, then the effor
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Student Worksheet

Thought starters: At home what percentage of your waste is recycled?

Step 1: The world of recycling aluminium cans

This table has the percentage recycling rates of aluminium cans for 11 countries for the years 2002 and 2010.  

Percentage recycling of aluminium cans for 2002 and 2012
Country Percentage Recycled 2002 Percentage Recycled 2010 Percentage Improvement
Australia 63% 67%
France 30% 57%
Germany 78% 96%
Italy 50% 72%
Japan 83% 93%
Portugal 27% 45%
Spain 25% 61%
Switzerland 91% 91%
Sweden 86% 87%
UK 42% 54%
USA 53% 58%

1. In the table above calculate the percentage improvement for each of the 11 countries (hint minus the percentage for 2002 from 2010). 

2. Which country has the highest recycling rate of aluminium can for 2010? 

3. Which country has the greatest improvement in recycling rates?

4. Produce a graph of recycling rates for the 11 countries. Th

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