Activity Introduction

Quick summary: Students will analyse recycling and contamination data. They will use mean, median, mode and outliner mathematical concepts and identify when each of these can help in an analyses. Students will examine recycling in EU countries, a school waste survey and a council recycling contamination reduction program. They will produce a postcard to help people avoid contaminating the recycling. 

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 intentions:

  • Students apply the use of mean, median, mode and outliner mathematical to data sets.

21st century skills: 

  Critical ThinkingProblem Solving              

Australian Curriculum Mapping

Year 9 Mathematics:

  • Compare data displays using mean, median and range to describe and interpret numerical datasets in terms of location (centre) and spread (ACMSP283)

Time needed: 120 min 

Level of teacher scaffolding: Medium – discuss why some of the different concepts help us understand a problem.

Resources needed: Consider using a spreadsheet application.

Digital technology opportunities: Video and spreadsheets.

There’s an app for that: iRecycle: iRecycle provides access to more than 1,600,000 ways torecycle over 350 materials.

Assumed prior learning: Sorting waste into rubbish, recycling, reusing and composting, familiar with applying percentage.

Keywords: Contamination, recycling, mean, median, mode and outliner.

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

Overarching learning goals: Apply the use of mean, median, mode and outliner mathematical to data sets.

Teacher content information: After our recycling bin is emptied into a truck, it is taken to a MRF (Materials Recycling Facility). In the factory the materials are sorted. Some are baled after being sorted. All the contamination must be removed. Once sorted, the materials are then sent to recycling factories where they are processed.

Contamination of household recycling is a significant issue. Plastic bags can get caught in machinery and the machines will stop and need repairing. A common issue is people putting their recycled materials into plastic bags. Not only are the bags a problem, but the bags need to be ripped open. Common materials that contaminate the recycling are:

  1. Plastic bags  
  2. Food waste and other green waste
  3. Shrink wrap, wrappers
  4. Large items
  5. Nappies and tissues
  6. Building materials
  7. Paper soiled by food (such as pizza boxes)


- or - to view worksheets

Student Worksheet

Thought starters: when you think about a contaminated drink, what comes to mind?

Step 1: What happens to our recycling?

Sorting Your Recycling - Video 1

Brainstorm the types of materials that can be recycled and the types of materials that cause contamination. 

Step 2: EU Recycling

Mathematics Terms

Mean: is the sum of all the values divided by number of items for which there are values.

Median: is the middle value out of a series of values. All the values are lined up from smallest to largest and the middle value is lined up. When there is an even number of values, then there will be two values that are in the middle. In this case, the average of the two values is the median. This can be a valuable way to analyse data when some of the data distorts the mean. An example is the average wage and the mean wage can be different because a few high wage earners can have a large effect on the mean.  It is useful to compare the mean and medium.

Mode: is the

- or - to view worksheets

Leave your Feedback

We appreciate your feedback. Let us know what you like or don't like about this activity:

Sorry. You must be logged in to view this form.