ABSTRACT
The origins of the class inclusion task can be traced to Piaget’s (1921) early study on children’s understanding of the concept of a part. Briefly, he found that children aged 10-14 years tended to misinterpret sentences in which one thing was said to be part of another. For example, some children were found to interpret a sentence such as “Part of my flowers are yellow” as meaning “My part of the flowers are yellow.” In this early phase of Piaget’s research, children’s reasoning was studied on an entirely verbal level. In Judgment and Reasoning in the Child (Piaget 1924/1928), he argued that children’s reasoning and logical thinking developed from their need to justify themselves in the context of interpersonal argument.
