In this video, chemical scientists of the University of Nottingham, UK explain how to do this experiment. You can try it yourself in your school lab, with the help of your teachers!
(Video titled "periodicvideos - February 22, 2010 - The traffic light reaction sees a solution change colour from green to red to amber. " sourced from http://www.youtube.com/watch?v=_YO4UPTjMVI&feature=channel)
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