ABSTRACT
This chapter deals mainly with the differences between several categories of children. Most children who discover the solution during the pretest are able to solve all standard inclusion problems afterward, irrespective of their material content. Children placed in the categories need more than one item explained to them in order to solve the problem. There is no evidence that the children learned anything more general than the capacity to handle standard inclusion problems. Some children, however, have to be helped a little with the transition from one material to another. Children of this category are able to justify their answers with good and logical arguments, do resist countersuggestions, and can grasp inclusion questions when confronted with new items. Jean-Claude Lasry’s study showed that these children made no appreciable progress in some tasks that, according to Jean Piaget’s theory, are closely connected with the capacity to answer the inclusion questions correctly.
