This session aims to explore the distribution of aquatic invertebrates on the bed of a stream and to examine the factors that may influence their distribution. First, the session will involve a short field trip to a stream (within walking distance of the university) to collect invertebrate samples and to record the environmental characteristics where they occur. Second, the session will involve a laboratory session involving the processing and identification of the invertebrates collected in the field. Finally, the session will examine the data collected and explore the reasons for the geographical patterns recorded in the field. Information sheets can be taken away to be used by teachers in the classroom. Any provisions students need to bring: pencil, notebook and wellington boots (if they can).