A few pioneers have been experimenting in this field for some years past. No one of them is ready with final conclusions but among them opinion is unanimous that constructive play is stimulated by an initial supply of consistent play material calculated to suggest supplementary play material of a kind children can manufacture for themselves.
Blocks are of course the most important type of initial material to be provided; beyond this the generally accepted hypothesis is embodied in the "Do-with" series which provides, first a doll family of proportions suited to block houses, then a set of farm animals and carts, then a set of wild animals, all designed on the same size scale, of construction simple enough to be copied at the bench, and suggesting, each set after its kind, a host of supplementary toys, limited in variety and in numbers only by the experience of the child concerned and by his ability to construct them.
This working hypothesis for the selection of toys is as yet but little understood either by those who buy or those who sell play materials. The commercial dealer declares with truth that there is too little demand to justify placing such a series on the market. Not only does he refuse to make "Do-withs" but he provides no adequate substitutes. His wooden toys are merely wooden ornaments without relation to any series and without playability, immobile, reasonless, for the philosophy of the play laboratory is quite unknown to the makers of play materials, while those who buy are guided almost entirely by convention and have no better standard by which to estimate what constitutes their money's worth.
On the other hand enthusiasts raise the question, why supply any toys? Is it not better for children to make all their toys? And as Miss Pratt says, "getting ready for play is mistaken for play itself."