Teacher Preparation

Overarching learning goal: By participating in this activity students will understand the environmental risks of sending waste to landfill, and the social, environmental and economic benefits of recycling green waste. Students will also understand life cycle thinking in relation to green waste and how green waste can be turned into compost to improve soil health.

Teacher content information: Many people think that sending green waste to landfill is fine. It’s natural right?? Surely it just breaks down and creates good soil that helps the environment?? No, sadly, this is not what happens at all.

Landfill sites are essentially great big piles of rubbish. There is no air in these great big piles and this means nothing much breaks down in them at all (did you know that old landfills are now being treated as archaeological sites because the waste is so well preserved?!). The only organisms that can survive in a landfill are bacteria which decomposes the waste anaerobically (without using oxygen). Unfortunately when they go to work to break down organic material like green waste and food they create methane, a greenhouse gas that’s 20 times more potent than carbon dioxide. The average Australian household produces about 700kg of greenhouse gas emissions from food and garden waste each year, about half from each.

Organic waste decomposing anaerobically in landfill also produces leachate, a liquid that’s created as waste materials decompose. Leachate is made up of decomposed materials plus rain, when it falls on the landfill site. Because this leachate contains substances harmful to the soil, groundwater and waterways it must be carefully managed to ensure it is contained.

If green waste is put in your green waste bin, it is sent in a truck to a facility where it is composted. Composting is a natural process of decomposition using oxygen (aerobically) that is better for the environment. The little decomposition critters that can survive in a composting system don’t produce methane like the bacteria in landfill. Furthermore, composting turns green waste into a range of high quality, natural soil conditioning products such as mulches, composts, blended soils and potting mixes used in landscaping, horticulture and agriculture. These products take green waste back to earth, enriching the soil and helping to grow healthy crops and pastures that produce food for everyone. Today’s green waste can grow tomorrow’s lunch! You’ll never look at your lawn clippings in the same way again…

Students should work in groups to complete this activity. Groups can complete all the points or stages of the green waste life cycle. Alternatively, the points or stages of the green waste life cycle can be divided and addressed by different groups.

Student and classroom organisation

Teaching sequence

20 minutes – Introduction, reviewing waste words and definitions and reading through Back to Earth website.
40 minutes – Researching life cycle.
40 minutes – Creating movie or animation.
10 minutes – Presentation of movie or animation.
10 minutes – Reflection questions.

Step 1.

Begin by reviewing the following words and definitions with students by asking students to match the correct word with the definitions on the Student Worksheet:

Waste - Any material that is discharged, emitted or deposited in our environment in a way that causes a problem for our environment.
Organic waste - Any animal or plant based material and degradable carbon such as garden organics, food, timber, paper and cardboard.
Green waste - Biodegradable waste that can be composed of garden or park waste, such as grass or flower cuttings and hedge trimmings.
Food waste - Food that is discarded or cannot be used.
Compost - Decomposed organic material used as plant food.
Landfill - The disposal of waste into or onto land.
Contamination - To make (something) dangerous, dirty, or impure by adding something harmful or undesirable to it.
Sustainability - Sustainability could be defined as an ability or capacity of something to be maintained or to sustain itself.
Life cycle assessment - The evaluation of the environmental aspects of a product or service system through all stages of its life cycle.
Social benefit - The benefits of waste management and recycling to people, such as an improved natural environment, lower energy use, and a healthier environment for future generations.
Environmental risk - The potential risks to the natural environment from waste and waste mismanagement.

Once complete, ask students to share their answers and make corrections where necessary.

Step 2.

Ask students to read the following two pages from the Back to Earth website:

https://backtoearth.vic.gov.au/recycling-benefits.html
https://backtoearth.vic.gov.au/do-s-dont-s.html

Students should then respond to the associated questions on the Student Worksheet.

Step 3.

Explain to students that they will be exploring the life cycle of green waste by creating an animation or short movie that shows an item of green waste entering a kerbside green waste bin.

Students will need to select an item of green waste to follow (such as a leaf or lawn clippings) and look at the following points of the life cycle (also available on the Student Worksheet):

Production
Collection
Decontamination
Screening and Shredding
Composting
Grading
Recycled Compost

As part of their life cycle animation/movie students should also look at:

Where green waste comes from, what is green waste?
Which bin green waste goes into, what else goes in the bin, what stays out of the bin, and why this is important?
Where does green waste go once it has been collected by the truck? Students should investigate what happens to green waste in your area, such as where is your local resource recovery facility?
How it green waste composted, what is the decomposition process?
Where does green waste go after it is composted? For example some might be used by the local council for parks and gardens, some might be sold to farmers. Can you find out what happens in your area?
The benefits of this composting green waste versus sending it to landfill. Students should look at the social, environmental and economic benefits.

Students should work in groups to complete this activity. Groups can complete all the points or the points can be divided and addressed by different groups.

Students can use desktop animation or movie programs or online programs such as Wideo, Animoto and Pixorial.

Assessment

Ask groups to present their animations/movies to the class. Engage students in a brief discussion around presentations.

Reflection

Ask students to complete the thinking routine on the Student Worksheet.

Differentiated Learning

Extension:

Students could write a letter to a waste officer at their local council or an organic waste recovery facility asking them about the possibility of including food waste as part of their organic recycling program.
Contact the waste officer at your local council or organic waste recovery facility to organize a site visit/tour.

Provisional Learning Support: Ensure students with learning difficulties are teamed with more capable students.

Back to Earth - Green Waste Cycle

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