How clean is the Thames today? Different types of scientific inquiries help pupils discover what impact the river environment had on people’s health during the 19th and 21st centuries. These include using riverside observations, identification of river wildlife and signs of pollution. Fair testing will measure water quality (pH, turbidity and water temperature). Collecting, analysing and presenting data will allow pupils to be part of ‘River Watch’, a citizen science project. Data will be uploaded to the River Watch database, enabling classes to use it for follow-up work back at school. The data will also be used by scientists monitoring litter and water quality issues in the tidal Thames.