Earth Day Activity: How to Run a Classroom Garbage Audit

Earth Day is a good moment to move from “we should recycle” to “what do we actually throw away?” A classroom garbage audit does exactly that. Students collect real data about their own waste and use it to make a recommendation to someone who can act on it.

What you need

Disposable gloves (latex-free)
A kitchen scale that reads in grams
Three tubs or bins labelled Landfill, Recycling and Compost
Old newspapers or a tarp to cover desks
A printout of your town’s recycling and compost rules
Chart paper and markers

The method

Collect. Save one day of classroom waste in a bag, with the caretaker’s agreement. Don’t include anything wet, sharp or unsanitary.
Predict. Before opening, ask: what fraction will be recyclable? Compostable? Write guesses on the board.
Sort. Wearing gloves, teams sort the items into the three bins using your local rules. Tell students to stop and ask if they’re unsure.
Weigh. Weigh each pile in grams and record it.
Graph. Make a bar graph or pie chart of the three piles.
Compare. Which pile was biggest? Was anything in the wrong place? Was the prediction close?

Turn data into a recommendation

The real learning is the last step. Students write a short recommendation for the principal or caretaker, using this structure:

Claim: One change that would help most.
Evidence: The numbers from the audit.
Reasoning: Why that change would reduce waste.

A good recommendation sounds like: “Of 1,240 g of garbage, 520 g was paper that could be recycled. A paper recycling box by the door would keep it out of landfill.”

Safety and sensitivity

Gloves on, no touching faces, wash hands afterwards.
Never include food that could attract pests, and don’t let students handle sharp items. A teacher removes glass and needles.
Be careful about allergens in food packaging.
Make clear that the point is not to shame anyone.

Variations

Repeat after a change. If the school adds a compost bin, run the audit again a month later. A before-and-after comparison is a real experiment.
Different spaces. Compare the classroom, the staff room and the playground.
Estimate a year. If the classroom makes this much per day, how much would it make in a school year?

Our unit Earth Day Investigations: Make Your School Better includes the audit as What’s in our garbage?, plus Where would a new tree help most?, How much water does a dripping tap waste? and Is our classroom wasting electricity? Each ends with a recommendation. Sign up for three lessons free.