Play stimulates children’s creativity, learning, and development, which is why toys and games are undoubtedly…

The Notion of Unstructured Play for creativity development
Creative Playthings was established by Frank and Theresa Caplan in 1945 to provide simple and beautifully designed toys to promote a child’s imagination and creativity .
As many new enterprises, initially, they made hardwood building blocks themselves to sell in their store, often cutting and sanding the sets while customers waited in the shop. They then added vehicles, animals, people and other toys. Caplan wanted to provide unpainted abstract forms in order to emphasized shape, color and texture, as opposed to reality-like details. The idea was to trigger child’s imagination. These and other products exemplified the concept that design for the unstructured play is the way children can use their imagination and thus shape their individual personality, rather that play with determined forms made by manufacturers.
I like this quote from Caplan in the catalogue of 1949
Play has a basic role in the drama of a child’s development. It is a serious business for the child, his true means of learning and growing…Every child should have a wide variety of play materials to evoke in him a spirit of inquiry; to develop physical manipulation to the fullest; to stimulate creative expression. He requires not only the miniatures of real objects in the adult world, but also building blocks, clay, finger paints, et cetera, that he can adapt to his particular needs.