Keyhole Garden Keyhole Gardens are a great addition to any school grounds and will really help your pupils to learn about 'good news' projects in Africa. The design - which looks like a keyhole from above - incorporates a central ‘basket’ where compostable waste is placed and 'grey' (used) water is poured. They get brilliant results and are a fantastic whole school sustainability project. Hundreds of schools have used the gardens to talk about compost, recycling, food and life in African countries. Why not give it a go?