Industrial design challenge – separating materials lesson

Years 7 and 8

This lesson is a great introduction to the idea of separating mixtures and enables students to consider separation as a process that operates on macroscopic levels. It provides students with an opportunity to engage in hands-on engineering using recycled materials.

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    Lesson Plan

    Industrial design challenge – separating materials

    Years 7 and 8

Learning hook

According to WWF Australia, in 2017-18 Australians used around 3.4 million tonnes of plastics of which only 9.4 per cent was recycled. Of this amount, 46 per cent was reprocessed in Australia, and 54 per cent was exported for reprocessing.

Share these statistics with the class and ask them to sketch a representation to show the relative amount of plastic recycled in Australia. Note: some students may need additional support to identify an appropriate representation, and you can suggest they start with a pie chart.

As a class discuss why students think Australia’s plastic recycling is so low, and what initiatives they’re aware of that aim to reduce plastic waste.

Watch the Australian Story video (29 mins), where recycling revolutionary Professor Veena Sahajwalla turns old clothes into kitchen tiles, to explore the role of industrial innovators in creating preferred futures. 

Recycling revolutionary Veena Sahajwalla turns old clothes into kitchen tiles | Australian Story

Learning input

Separation of materials is critical to effective recycling. The co-mingled, mixed recyclables we collect need to be sorted into separate recycling streams at a specialised materials recovery facility (MRF).

A key piece of equipment in the process is the trommel screen, which separates materials moving through a perforated, rotating, cylindrical drum that sorts objects by size. Smaller materials pass through holes in the drum while larger materials make it across to the other side.

Watch this video to see how a trommel screen removes contaminants like plastic and cardboard from green waste.

Vermeer Trommel Screen sorting contaminants from green waste

Students can explore an advanced resource recovery facility by viewing this Cairns Regional Council virtual tour.

Learning construction

Part A

Students are to design a model that demonstrates a separation technique used in a materials recovery facility. They will work in groups to build a trommel screen and demonstrate its effectiveness at separating different types of waste.

Trommel Screen

Provide students with a range of materials to be separated – consider materials of different sizes and shapes, such as sand, small strips of paper, balls of aluminium foil and paper clips. Students should select four materials to use in their design.

The challenge is for students to create a trommel screen using recycled materials that separates each material into its own tray. Effective design doesn’t happen overnight, so encourage students to keep a design journal and record how they iterate on and improve their design.

They should also test the efficacy of their design throughout and record their investigations. Variables they may need to test include the size of the mesh or equivalent, the speed of the rotation and the angle of the screen when rotating.

Part B

To share the models, run an industrial design fair where students demonstrate their designs to their peers. Students can vote for different awards as they peruse the models:

  • Most innovative use of recycled materials
  • Strongest construction
  • Most efficient design
  • Most detailed design journal
  • Most rigorous testing.