There are a wide range of interactions between ‘science’ and ‘the public’. Examples range from visiting a museum, or indulging in a science-related hobby, to reading a newspaper article about a breakthrough in the techniques of therapeutic cloning. Many of these interactions could be said to be ‘passive’. This unit explores the practicalities of the public becoming more ‘active’ in the direction of science practice by ‘two-way’ interactions, with dialogue taking place between science and some part of ‘the public’, This study unit is just one of many that can be found on LearningSpace, part of OpenLearn, a collection of open educational resources from The Open University. Published in ePub 2.0.1 format, some feature such as audio, video and linked PDF are not supported by all ePub readers.