Why do we so often take the escalator, when we could use the stairs and get some exercise? Volkswagen Sweden attempted to answer this question by installing a life-sized keyboard in a Stockholm underground station. Each time someone walked on a step a note would sound, and the experiment proved a very popular as you can see here.

Few of us heed the advice we're given to exercise more (it can't just be me, surely!), but sixty-six percent more people chose the piano stairs over the escalator. The experiment was part of a campaign called The Fun Theory, a unique initiative to find out whether people were more motivated to change their behaviour if it became fun to do so.

Sweden has seen rising obesity rates in recent years, especially amongst young girls, and has pioneered a number of anti-obesity drives. Sadly for those of us wanting to combine our piano practice with step aerobics though, the piano stairs have now been taken away. Just as well, perhaps, before someone took a nasty tumble playing Chopsticks!