Keele Research Repository

The research was concerned with the development of understanding of invariant quantity in mentally handicapped children. In a series of investigations, 317 educationally subnormal schoolchildren aged 8 to 16 with IQs between 42 and 81 were pre-tested in Piaget-type situations for, variously, conservation of number, substance, length, distance, area, weight, and volume. Experimental groups of nonconserving children, matched to control groups of nonconservers, were given instruction on conservation and then post-tested some weeks later.

The five investigations, each of which is reported separately and in detail, provided answers to 6 central questions. First, it was found that it is possible to develop understanding of conservation in educationally subnormal children by instruction. Second, such understanding can be developed using teaching which includes a large amount of varied relevant experiences and explanations in concrete situations. Third, the understanding developed by instruction was shown to be generalised and durable. Fourth, a uniform sequence was found in the spontaneous development of conservation in educationally subnormal children: conservation of number before substance and length before weight before volume and area. Fifth, the particulars of the situation facing the child were shown to influence conceptual recognition of conservation of number, substance, area and volume and also perceptual recognition of continuing equality of length and area. Sixth, a child's response to teaching was found to be influenced by some interaction between his initial level of understanding and the fullness of the instruction given to him.