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  • Explore the science concepts that underpin how we classify and sort materials that are no longer useful to us.

    The concepts listed just above the overarching concepts reflect learning at New Zealand Curriculum level 1 and show how they may build in sequence. The overarching science concepts are fully developed concepts and might not be achieved until level 7 or 8.

    Some of the text is courtesy of the New Zealand Ministry of Education’s Building Science Concepts Book 60 Rubbish: How Do We Deal with It? The links to Hub resources provide additional background information and classroom activities that will support teachers to scaffold the development of their students’ conceptual understanding about the properties of rubbish and how we sort materials by their properties. The images provide a means to initiate discussions, check student thinking and consolidate student understanding.

    The Hub also has a curated resource on recycling and biodegradability that includes articles, interactives and images and provides links to citizen science opportunities.

    To use this interactive, move your mouse or finger over any of the green labelled boxes and select to obtain more information.

    Download a PDF file of the transcript here.

    The article Building Science Concepts: Rubbish provides additional science and pedagogical information.

    Transcript

    We can sort rubbish according to its properties

    We can sort (whakawehewehe) rubbish in a variety of ways using senses, material properties and origins (pūtake). Senses can be used to classify rubbish (rāpihi). Rubbish can be sorted by its properties as in the Physical properties of rubbish table and by its origins in the Waste classification table (pūtakenga).

    Rubbish can also be sorted by how we dispose of it. Food and organic material may be composted, and recyclable materials such as cans, plastics, glass are chemically altered during the recycling process.

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    Image acknowledgement: The University of Waikato Te Whare Wānanga o Waikato

    There are lots of different ways of grouping rubbish

    People sort (whakawehewehe) rubbish in a variety of ways whether it is according to its properties or by the recycling codes.

    Curated resource collection

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    Image acknowledgement: Lara Bieleski

    Recycling codes and practices are based on the properties of the materials

    Waste is classified based on the physical properties of rubbish (rāpihi). Rubbish is sorted into categories (rōpū, wehenga) so that it can be disposed of in the most effective way.

    Source separation is when the consumer sorts their rubbish into landfill and recyclable refuse. The transfer stations or recycling companies then sort (whakawehewehe) this material again according to the different properties such as colour.

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    Image acknowledgement: The University of Waikato Te Whare Wānanga o Waikato

    Rubbish made from the same type of material (for example, aluminium or cotton) will have some similar properties

    Identifying what an item is made from helps to work out the best disposal method. Glass comes in many different colours and shapes but has similar properties and is classified similarly in the classification phase.

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    Image acknowledgement: The University of Waikato Te Whare Wānanga o Waikato

    We can sort rubbish by using our senses

    Over time, some materials change their properties and may cease to be useful. Bread that was soft when fresh may go hard when stale, while fruit that was firm when fresh may go soft when stale. Food that we call stale is often classed as rubbish.

    Food may be discarded if it:

    • smells bad (haunga)
    • feels hard and stale or soft and pulpy
    • looks rotten, contaminated or mouldy (pirau)
    • tastes peculiar
    • sounds mushy or hollow.

    Other materials can be classified using our senses. Timber that feels soft may be rotten, rubber bands that feel hard may have lost their elasticity and be discarded and fabric may rip more easily when it has been in the sun too long. These changes in properties can lead people to classify these materials as rubbish and dispose of them.

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    Image acknowledgement: V Bootham

    We classify things as rubbish only when we decide that they are no longer useful to us

    What is rubbish? Rubbish refers to something that is no longer wanted or valued by the individual. One person may classify an old chair as rubbish, but it could be a treasure to someone who likes to renovate old furniture.

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    Image acknowledgement: sergiobarrios, 123RF Ltd

    People have different ideas about what can be classified as rubbish

    There are many ways that a person’s rubbish can become a useful item to someone else. Recycling centres, garage sales, second-hand shops and online sales of unwanted goods enable some items to carry on being useful and valued by someone else.

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    Image acknowledgement: Anne Barker

    If we are careful about how we use materials, we can reduce the amount of rubbish we produce

    We can reduce the amount of rubbish that we produce.

    We can reuse items rather than throwing them away.

    We can recycle items for similar or new uses. For example, old curtains can be remade into reusable shopping bags. Materials can be put through a chemical process to reuse the chemical components into new items. For example, plastic bottles can be used to make fleece clothing. Even composting is a chemical process that changes food and vegetable matter into compost for the garden.

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    Image acknowledgement: The University of Waikato Te Whare Wānanga o Waikato

    Rights: The University of Waikato Te Whare Wānanga o Waikato Published 8 March 2022 Size: 6.2 MB Referencing Hub media
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