Nina investigates how a bin lorry works - with the help of Ollie, her smell neuron. Engineers Heidi, Molly and Sam visit Nina in her workshop and discover that bin lorries use pistons to lift up the rubbish bins. Next they go to a recycling centre and find out that pistons are tubes connected with liquid. Lastly they visit the Thames Barrier which protects London from flooding.

Originally released by BBC Worldwide Learning, 2013. Streaming video file encoded with permission for digital streaming by Infobase on April 29, 2015.