He moved to the United States in 1964 to teach, first at the Moore College of Art and Design, Philadelphia, and later at the University of Berkeley, California.
Nicholson's work is characterised by an interest in the texture of different surfaces and materials, often taking the landscape as its starting point.
[4] His "Theory of Loose Parts", outlined in a 1971 essay, has been influential[5] in playwork, early education and interactive installations of all kinds.
He summarised the theory as: "In any environment, both the degree of inventiveness and creativity, and the possibility of discovery, are directly proportional to the number and kind of variables in it.
The definition could be even broader: There is evidence that all children love to interact with variables such as materials and shapes; smells and other physical phenomena, such as electricity, magnetism and gravity; media such as gases and fluids; sounds, music and motion; chemical interactions, cooking and fire; and other people, and animals, plants, words, concepts and ideas.