Grown using the Miyawaki method, fast-growing miniature forests in the middle of cities can bring surprisingly big benefits for people and the environment. "It's like going on a bear hunt!" Not quite, perhaps, but these kids are definitely excited. They are on a visit to a miniscule patch of forest in the grounds of Queen Margaret University on the outskirts of Edinburgh, Scotland, and are about to head out armed with a bucket of water, a jug and a stopwatch. They are measuring how fast patches of soil inside and outside the forest absorb water, so we leave the small circular howff (a traditionally-built shelter with a wildflower roof) in the middle of the vegetation. The child in charge of the stopwatch does a couple of test runs and the pouring begins.