The Science Teaching Project of the Nuffield Foundation was concerned with the curriculum development in the subjects of physics, chemistry and biology where the emphasis was on discovery and understanding rather than on learning and recalling facts. The Science Teaching Project considered it important to recognise the essential unity of the physical sciences and, in particular, the existence of common ground between physics and chemistry. O Level trials ran in 150 schools for 1964/65 and 1965/66 and the Nuffield courses became publicly available in 1966. It was intended that trials for A Level courses in biology, physics, chemistry and the physical sciences should commence in 1966 with the courses becoming publicly available in 1969.