Main content

Using maths to recycle rubbish

Stefan Gates explores how shapes are used to sort and re-use rubbish at a recycling plant. He helps children sort their recycling and then shows them what can be made out of it.

Stefan Gates finds out that machines can sort rubbish into different 2D and 3D shapes when he visits a vast recycling plant. He speaks to Richard Kirkman who explains how they use different machines to sort the rubbish by weight and shape. Stefan throws some items from his own recycling into a machine like a giant sieve – a cylinder (plastic bottle), a flat rectangle (piece of paper), and a cube (cardboard box). We see that the machine lets some shapes through but others travel across onto a conveyor belt. The different machines and conveyor belts continue to separate the different materials. At the end a machine squashes them into cuboid bales of the same size and shape, but made from different materials – cardboard, aluminium or plastic. Stefan shows us the new items that can be made from the recycled material - cardboard boxes, drinks cans, plastic bottles and a recycled plastic chair. Stefan then visits pupils from John Donne School in South London who show him how they reuse plastic bottles by first sorting them into different sizes and shapes, just like the machines. Then they can make new things out of them, from bird feeders to planters to a whole greenhouse with walls made from 1500 plastic bottles.

Release date:


10 minutes

This clip is from