A load ofrot

Year level

Middle PrimarytoUpper Primarywith extension activities for older students listed at end of lesson plan.

Lesson description

Students make their own mini compost bins to observe changes that occur over time as materials decompose.

In this lesson students will become aware:

  • that natural processes can break down and recycle some waste
  • that composting is simply speeding up the decomposition process that occurs naturally by providing the ideal conditions for this breakdown to occur
  • that some materials are suitable for composting and some are not
  • of the factors that affect the speed of decomposition
  • that compost is full of nutrients and acts as a natural fertiliser

Curriculum links

Year 3 and 4

Investigate food and fibre production and food technologies used in modern and traditional societies (Design &Technologies - ACTDEK012)

Years 3 and 4

Investigate the suitability of materials, systems, components, tools and equipment for a range of purposes (Design & Technologies - ACTDEK013)

Year 4

The natural resources provided by the environment, and different views on how they could be used sustainably (Geography - ACHGK024)

The sustainable management of waste from production and consumption (Science - ACHGK025)

Living things, including plants and animals depend on each other and the environment to survive (Science - ACSSU073)

Years 5 and 6

Investigate how and why food and fibre are produced in managed environments (Design & Technologies - ACTDEK021)

Year 6

The growth and survival of living things are affected by the physical conditions of their environment (Science - ACSSU094)

Materials

  • 1 x two litre soft drink bottle with top cut off for each student or group
  • Compost materials such as grass, fruit and vegetable scraps, dried leaves, coffee Grounds, straw and scrunched newspaper
  • 2 or 3 Tablespoons of garden soil or compost for each bottle
  • Square of calico, cotton or paper and elastic band to cover each bottle
  • Poster ‘What goes in a compost bin?’(available on Brisbane City Council website)
  • Permanent marker
  • Water
  • Small container of compost

Procedure

  1. Show students the small container of compost and explain that compost is formed when plant and vegetable matter breaks down. Composting and worm farming are both forms of organic recycling.
  1. Explain the benefits of composting.

Including:

  • Compost is a great resource that is full of nutrients and helps to improve soil quality. It is a wonderful fertiliser that will help your vegetable, herbs and other plants to grow.
  • Approximately half of our waste that ends up in Brisbane Landfill is organic waste that comes from our kitchens and gardens. Composting this waste would save valuablelandfill space.
  • Compost improves the structure of soil and enhances its ability to hold water.
  1. Discuss the ingredients for compost:
  • Green waste (nitrogen rich) material such as fruit and vegetable scraps, coffee grounds and fresh grass clippings
  • Brown waste (carbon rich) material such as dried leaves, dried grass, straw and paper
  • Water
  • Air

Explain that green waste is quick to break down and adds moisture, while brown material is slower to break down and is full of carbon and that it is essential to include both green and brown waste to make good compost.

  1. Discuss materials that should not go in a compost bin such as meat scraps, dairy products, cooked food, oil, plastic and so forth.
  1. Demonstrate to students how to build the compost layers in the bottle and the importance of mixing the ingredients. Start with 2 or 3 centimetres of soil at the bottom of the bottle, then add a 2 or 3 centimetres layer of green materials (such as vegetable scraps), a sprinkling of soil and then some brown materials (such as scrunched newspaper or dry leaves). Continue alternating brown and green materials, sprinkling soil between the layers until bottle is full. Finish off with a layer of soil at the top. Explain to students that the soil contains microorganisms which will greatly speed up the process of decomposition.
  1. Once the container is full sprinkle with water and then place covering material over the top and secure with elastic band.
  1. Use the permanent marker on the side of the bottle to markthe layers of the organic material and the soil.
  1. Once students have made their own bottled compost have them attach a piece of tape with their name and the date to the bottle.
  1. Students observe and record any changes in the compost every day for the next few weeks including changes in the appearance of materials. After four weeks students use a different coloured pen to mark the new levels of the organic layers and the soil layers and discuss the reasons for these changes.

Extension activities

  • Set up five mini compost bins with minor changes between each and observe differences in the decomposition rates of materials in each of the bins.
  • Bury one of five different objects in each bin such as an apple core, a cardboard juice box, a piece of office paper or a carrot and compare differences in decomposition rates.
  • Put some holes in the bottom of container and add some worms to make a mini worm farm. Worm farm will need to be placed on a couple of small blocks over a tray so that worm juice can drain out.
  • Set up a composting system within the school and arrange to have compost monitors who collect the compost materials from classrooms to add to the bin.
  • Plant seeds and /or seedlings in the compost and compare them with seeds or seedlings planted in garden soil.

Brisbane City Council

Rethink Your Rubbish Lesson Plan: Organic Recycling – A Load of Rot