The River Clyde in Scotland is famous worldwide for its former commercial life, with trade and shipbuilding concentrated at the tidal end of its 170 km length. Nowadays the river is quieter but cleaner and is recovering from centuries of manmade changes to its bed, banks and flows. The Clyde River Foundation (CRF) is a registered Scottish charity that researches the ecology of the River Clyde and its tributaries, and promotes public engagement and environmental education across eight counties. In January 2023, the Clyde River Foundation will welcome the 40,000th student to its biggest primary school project, 'Clyde in the Classroom' (CITC). CITC involves mimicking part of the life cycle of a native species, the brown trout, by raising fish from eggs to the fry stage in a classroom hatchery. When they are ready, the fish are released by the children under licence to the nearest safely accessible watercourse to the school, hopefully engendering a degree of ownership and environmental responsibility. Since Clyde in the Classroom was launched in 2001, a total of 1434 hatcheries have been cared for by 38,407 children and the project is now into its third decade.