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What's Waste
(from Lesson 2 - Waste Charaterization)

In this lesson students will learn what is in waste, and consider how to reduce the quantity of waste.

Use of the book:
Teacher background on waste characterization: p.48-50
Teacher notes on activity: p.51-53.
Student instructions for activity: p.54-55
Data recording/Analysis questions: p.56-58

Materials Needed:
per group:
Bag of trash (Note: Have several colleagues collect “clean” trash. This means that containers are washed and food is placed into separate plastic bags. This way, the activity is cleaner, we can re-use the non-food items, and we can also compare different people’s trash.)
Large trash bag (to be cut open), scissors
7 plastic bags (grocery store type), triple-beam balance, bathroom scale (can get manage with less than one per group), calculators (2)
per student:
goggles, rubber gloves (2)

p.54-55 back-to-back and laminated for directions
p.54-55 on overhead transparencies
p.56, 57, 58 back-to-back for participants
p.48, 56, 57 on overhead transparencies

Opening Strategy: p.52
How many of you take the trash out at home? How many bags/containers each week? Where does it go? What would happen if no one picked it up? What types of things do you throw away in your garbage?

Procedure: p.54-55
1. Measure mass of entire bag of trash. Probably need to use bathroom scale rather than balance. (If scale is in lbs, will need to convert to metric – 2.2 lbs. = 1 kg.) Teach students how to weigh themselves first, then get student + bag of trash weight, then subtract student weight.
2. Cut open large trash bag. Spread out on floor.
3. Put on goggles and rubber gloves. Sort and classify trash. Record on data sheet p.56.
4. Put each category in a plastic bag (get bag’s mass first). Find each mass using the triple-beam balance. Record in data table p.56. Remind students to subtract the mass of the plastic bag.
5. Calculate the percent of total mass for each category:
mass of category  X 100
    total mass

Discuss with students how you want them to round their percents. Decide if calculators are allowed. If I allow calculators, I require students to write out the equation and show their work.
6. Plot your percent data on the bar graph p.57 in the “class” columns.
7. Answer questions p.57-58.

Note: I think it is optional to do steps #8-9 now depending on your students’ prior knowledge about reusing, recycling, composting at this time. If you do these steps now, you will first need to discuss these terms (especially composting).

8. Determine the mass of items removed for reuse, recycling, or composting. Record on p.56.
9. Determine the total percent by mass of all reusable, recyclable, and compostable items removed:
mass of items removed   X100
initial total mass of bag

10. Clean up.
11. Discuss.

Garbage Bag

Recycle Bin
graphics - courtesy of the
Wisconsin Department of Natural Resources


  • Overhead transparency - Use pie graph p.48 to compare with bar graph.
  • Do this activity with students collecting their own garbage for a day. This may require a note home to parents in advance. Do not collect personal hygiene or waste products.
  • At the end of the unit, repeat the activity and see if students have decreased their amount of trash by increasing their reusing, recycling and/or composting.
  • Extensions, Cross-Curricular Integration: p.53.
    • Look at amount of trash per household, per classroom, per school.
    • Do daily amounts vary?
    • Art – creative uses for some items in the trash (see Activity: Treasures From Trash, p.128-135 (in Lesson 5 – Reusing Materials).
  • The Garbage Gazette: p.59-60.
    • “ Gargage Takes A Vacation” – garbage barge
    • “ Archeologists Find Garbage Tells The Truth” – UA Garbage Project

Southwest Environmental Health Sciences Center
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PO Box 210207, Tucson, AZ, USA 85721-0207

Funded by NIEHS grant # ES06694

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Last update: November 10, 2009
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