Teacher Preparation

Overarching learning goal: In this simple experiment the class will have the chance to study the different ways that waste materials break down. The class will bury a variety of ‘waste’ materials and dig them up at regular intervals to see how they are breaking down.

Teacher content information:

Biodegradation times depend on the environmental conditions. Materials will break down faster when exposed to the elements (sunlight, heat, rain, etc) and decomposers (fungi, bacteria, insects and other invertebrates). Landfills are not ideal environments for decomposition, so trash in landfills takes much longer to break down.

Print a copy of each waste flashcard, sticking the two sides of the card together so that the breakdown rate corresponds to the correct waste type. The breakdown rates for the flashcards are as follows:

Banana - 3-4 weeks
Tin cans - 200-500 years
Plastic rings from six pack - 450 years
Sock - 1 year
Leather boot - 40-50 years
Paper bag - 1 month
Glass bottles - unknown

Student and classroom organisation

Step 1:

Ask your class to think about the different types of waste that we make. Think of the things that you throw out everyday. What are they made of? What happens to this waste if it is just thrown onto the ground? Does it stay there forever or does it slowly break down and disappear?

Can you predict what happens to different materials such as paper, cardboard, glass, steel, aluminium, food, clothing and different types of plastic (glad-wrap, plastic bags, milk bottles and water bottles).

Step 2:

Using the Student Worksheet 'What will happen to the waste you buried?' get students to record which waste materials they predict will have a fast or a slow break down rate. In left-hand column table draw the types of waste that you think will break down quickly. In the right-hand column draw the types of waste that you think will break down slowly.

Step 3:

Conduct an experiment to test breakdown rates. Bury materials in a school garden or in a soil box. Dig out the materials weekly and record the results. Discuss with students:

What waste is breaking up fastest?
Which ones are taking the longest?
Why do you think some are faster than others?

Using the worksheet students can record what they found out about the waste that you have buried. In left-hand column of the table t hey can draw the types of waste that break down quickly. In the right-hand column draw the types of waste that break down slowly.

What Happens to Waste Experiment

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