Introduction

Recycling works best when the right materials end up in the right bins. Unfortunately, recycling contamination is a widespread issue across the United States and Canada. When trash, food, or the wrong type of material is mixed into recycling, it can increase costs, damage equipment, and cause entire loads to be rejected and sent to landfills. 

Professional recycling facilities measure contamination by weight, and their standards can be very strict. For decades, the U.S. recycling industry has relied on selling recyclables in international markets to help manage its municipal waste. In 2018, China set a 0.5% standard for contamination levels that most exporters of recyclables could not meet, leading to increased focus on internal recycling processes. In the US, the average contamination rate is estimated to be approximately between 15-25%, highlighting the gap between ideal recycling standards and real-world practices.
Source: U.S. GAO

In Canada, contamination of recyclable materials is also a problem, costing recycling programs millions of dollars. Many cities are struggling to lower their contamination rates, but the potential solutions also have high costs and trade-offs. In 2018, Toronto and Edmonton had contamination rates upwards of 25%. Vancouver and Montreal’s contamination rates were much lower, at 4.6% and 7.5% respectively. Effort and education are crucial to improving the quality of recyclable products.
Source: CBC News

This project helps students see the issue firsthand. By conducting a school recycling waste audit, students will sort, weigh, and analyze recyclables from different school locations. They will calculate contamination percentages and propose ways to reduce contamination at school. This project is hands-on and action-oriented, designed to help students become more aware of waste in their immediate surroundings and empowered to make positive changes. 

Note: Acceptable recyclable materials vary by municipality. Teachers should review local recycling guidelines before beginning the audit to ensure accurate sorting.

Suggested Timeline

• 1 Class: Launch
• 1 Week: Audit in Action
  • Note: Sorting and weighing may take longer than a single class period. Plan extra time for setup and cleanup, or split data collection and sorting across days if needed.
• 1-2 Classes: Analysis and Reflection

Student Objectives

Students will be able to 

• Define recycling contamination and explain its impact.
• Conduct a recycling waste audit through collection and sorting.
• Measure waste categories by weight and calculate contamination percentages.
• Compare real school data to industry benchmarks.
• Collaborate in teams with assigned responsibilities.
• Propose evidence-based strategies to reduce contamination.

Materials (per team)

• Student Handout
• Gloves (reusable washable gloves or disposable gloves) 
• Tongs or grabbers (at least one)
• Trash bags or containers labeled for categories (recyclables vs. contaminants)
• A digital scale
• Tarp or covered table (e.g., with newspaper) for safe sorting.

Procedure

Before You Begin:
Check in with school administrators and custodial staff before starting the audit to confirm which bins can be used, when collections occur, and where sorted materials should be returned or disposed of.

1 Class: Launch

• Provide each team with the student handout, and complete Part 1: What Is Contamination in Recycling Waste? in groups or as a whole class. 
• Discuss China’s strict 0.5% contamination rule for recycling waste imports and the average rate of recycling waste contamination in the U.S. and Canada. Have students hypothesize what the school’s recycling waste contamination rate is.
• Discuss audit procedure and rules, as laid out in the Student Handout. Form student teams (3-5 students) and assign each team a specific bin or location that they will be responsible for auditing.
• Review safety guidelines, as outlined in the Student Handout.
• Review what materials are acceptable recyclables, based on local ordinances, and what would be counted as contamination.

1 Week: Audit in Action (Instructions also included in the Student Handout)

• Collection: Each team gathers content from their assigned bin(s) at a set time each day. Note: If hazardous or unsafe items are found (e.g., broken glass, needles, spoiled food), stop sorting that bin and notify the teacher immediately.
• Sorting: On a tarp, covered table, or designated indoor space in case of bad weather, students divide the contents into two categories: acceptable recyclables and contaminants.
• Weighing: Weigh the total bin contents, weigh the contaminant pile, and record both numbers.
• After weighing and recording data, return acceptable recyclables to the appropriate recycling stream and dispose of contaminants according to school procedures.
• Calculation: Calculate daily contamination percentage by dividing the weight of contaminants by the total weight of recyclables. 
• Record results: Students will record results on their team data sheet. 
• Note: Students who are uncomfortable handling waste can take on roles such as recorder, photographer, data analyst, or discussion leader.

1-2 Classes: Analysis and Reflection

• Compile all team Weekly Summary data into a class chart. Use the template below to create a shared chart where each team can record its information. This chart can be displayed on the classroom wall, set up as an online spreadsheet, or recreated on a whiteboard.
• Note: Real-world data is often messy. Variations between days or teams are expected and can lead to meaningful discussion about human behavior and systems.

All Teams Weekly Summary Compilation

• Students will complete the analysis and reflection section of the Student Handout, interpreting team results, comparing results to the contamination standards, and evaluating school recycling trends. 
• Students will brainstorm steps they could take to reduce recycling contamination at the school, and write an action plan proposal in a letter to the principal.

Teacher Considerations (Before You Begin)

• Coordinate with school staff:
  Check in with administrators and custodial staff before starting the audit to confirm which recycling bins can be used, when collections occur, and where sorted materials should be returned or disposed of.
  
• Review local recycling guidelines:
  Acceptable recyclable materials vary by municipality. Review local recycling rules in advance so students sort materials accurately.
  
• Plan for time and cleanup:
  Sorting and weighing materials often takes longer than expected. Plan extra time for setup and cleanup, or split collection and sorting across days if needed.
  
• Follow safety protocols:
  Students should always wear gloves and use tongs when handling waste. If hazardous or unsafe items (e.g., broken glass, sharp objects, spoiled food) are found, stop sorting that bin and notify the teacher immediately.
  
• Support student comfort and accessibility:
  Students who are uncomfortable handling waste can take on alternate roles such as recorder, data analyst, photographer, or discussion leader.
  
• Expect real-world data variability:
  Contamination rates may vary widely between bins and days. Inconsistent or unexpected results are normal and can lead to meaningful discussion about behavior and systems.
  
• Plan for disposal after the audit:
  After data is recorded, return acceptable recyclables to the proper recycling stream and dispose of contaminants according to school procedures.