Pluralization instruction in comprehension and production.

Four retarded children who did not comprehend or produce plurals were taught to pluralize by adding /s/ to words like hat/hats, cup/cups. Half of the children were first taught the rule in comprehension (pointing to single and multiple arrays of objects) and then in production (labeling the same arrays). The remaining two children were taught first to produce and then to comprehend plurals. In each sequence, one child demonstrated facilitation from the first taught modality to the second, as evidenced by rapid and efficient learning of the rule in the second modality. The sequence in which comprehension and production were taught did not affect the facilitation, however. The children were taught in two environments, an experimental room and an ordinary classroom.