Dallas hits the streets to discover what makes people happy, while Liz travels to Norway to investigate the latest technology to combat climate change. Jem puts himself in harm's way in avalanche country, and Dr Yan sets an optical illusion challenge to a WI meeting.

The programme is co-produced with the Open University. For more ways to put science to the test, go to www.bbc.co.uk/bang and follow the links to The Open University. Show less