Teacher Preparation

Overarching learning goal: In this activity, students look at waste and the time frame it takes to decompose. Students are asked to order a selection of waste materials into the time it takes for them to break down. In the closing activity, they will act as archeologists undertaking a dig of a kitchen 100 years in the future and are asked to describe the condition of the items that they find.

Teacher content information: Print a copy of the Waste breakdown flashcards, 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.

Introduce this activity to your students by holding a brief discussion about waste. Use the following questions to engage students (suggested answers included):

What is waste and where does it come from? – Stuff that we no longer want, such as packaging, unwanted household or industrial items, or left over food.
What happens to waste and where does it go? – Some types of waste break down quickly (like paper or fresh food) but other types of waste can take a very long time to breakdown, and so may stay in our environment for years and years.
Why is it a problem? – A lot of waste is slow to breakdown. When left in our environment it can be the source of terrible pollution and environmental damage. Also, when some types of waste break down they release chemicals that are harmful to our environment.
Can students think of any examples of waste causing serious environmental problems? - The Great Pacific Garbage Patch, pollution of freshwater sources like rivers and lakes, environmental damage from landfill sites leaching contaminants.

Step 2.

Ask students to think about the breakdown or decomposition of waste (includes suggested answers):

What does decomposition mean? – It means the breaking down or rotting of materials into smaller and smaller parts.
Where does something go when it has decomposed? – It becomes part of the natural environment.
How do things decompose? – Most organic items (items made from natural materials) decompose with the help of tiny animals or microorganisms. Some chemical materials never decompose.

Step 3.

Lay the Waste breakdown flashcards out on the floor explaining that these are common types of waste that are produced by households. Ask students to think about how long each item will take to decompose or breakdown. Working as a class, ask students to arrange the cards into a line showing the waste item with the shortest breakdown time at one end, and the one with longest breakdown rate at the other end. Ask students not to turn over the cards until everyone in the class is happy with the order of the line.

Step 4.

When the line is complete ask students to turn the cards over and talk about how their guesses correspond with the actual breakdown rates:

Which ones did they get right?
Which ones did they get wrong?
Why do they think some things take so long and others are pretty quick? You will notice that the more natural an item is the faster it will break down, but greater levels of manufacturing or processing will probably mean the item will take longer to break down (for example the banana is very fast as it is all natural but the tin cans have been created through a heavy manufacturing process so will take much longer even though are created from tin which is a natural substance). Some items will breakdown evenly while others will have bits and pieces that are faster or slower to breakdown (for example the leather on the leather boot might be faster that the eyelets for the laces or the plastic soles).

Step 5.

Ask students to rearrange the cards so that they are in the correct order.

Assessment/Reflection

Ask students to imagine that they are archeologists working 100 years in the future. They have been asked to excavate the kitchen of an Australian house that was buried by mud when a river burst its banks during a big storm. It’s the job of the students to record the condition of items that are found there. Students can draw the items or create them with modelling clay. Students should try to show how the items look and at what level of decomposition they might be. Each item should also be accompanied with a label or short description that talks about the condition of the item in more detail and why it's at its current level of decomposition.

Ask students to ‘find’ and describe the following items:

Plastic salad bowl
Wooden chopping board
Packet of chocolate biscuits
Bag of coffee beans
Ceramic teapot
Knife and fork
Water glass
Box of cereal
Kitchen sink
Tea towel

Waste breakdown

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