An experimental analysis of the claim that individual constructive activity is social was carried out using two categories of interactions, subjective-environment interactions and interactions of operations within the individual. The primary question of the analysis concerns the contribution of these two kinds of interaction to the individual construction of a mathematical scheme called the equi-partitioning scheme. It was found that interactions of operations within the individual were the principal interactions contributing to the construction of the scheme. It was further found that these interactions were occasioned by subject-environment interactions. But the subject-environment interactions could not be used to explain the individual construction of the scheme.

The basic hypothesis of the teaching experiment, The Child’s Construction of the Rational Numbers of Arithmetic (Steffe & Olive 1990), was that children’s fractional schemes can emerge as accommodations in their numerical counting schemes. This hypothesis is referred to as the reorganization hypothesis because when a new scheme is established by using another scheme in a novel way, the new scheme can be regarded as a reorganization of the prior scheme. In that case where children’s fractional schemes do emerge as accommodations in their numerical counting schemes, I regard the fractional schemes as superseding their earlier numerical counting schemes. If one scheme supersedes another, that does not mean the earlier scheme is replaced by the superseding scheme. Rather, it means that the superseding scheme solves the problems the earlier scheme solved but solves them better, and it solves new problems the earlier scheme did not solve. It is in this sense that we hypothesized children’s fractional schemes can supersede their numerical counting schemes and it is the sense in which we regarded numerical schemes as constructive mechanisms in the production of fractional schemes (Kieren, 1980). Relevance: This paper relates to Ernst von Glasersfeld’s reformulation of Piaget’s concept of scheme.

Key words: Equi-partitioning scheme, numerical counting scheme, connected numbers

Learning trajectories are presented of 2 fifth-grade children, Jason and Laura, who participated in the teaching experiment, Children’s Construction of the Rational Numbers of Arithmetic. 5 teaching episodes were held with the 2 children, October 15 and November 1, 8, 15, and 22. During the fourth grade, the 2 children demonstrated distinctly different partitioning schemes-the equi-partitioning scheme (Jason) and the simultaneous partitioning scheme (Laura). At the outset of the children’s fifth grade, it was hypothesized that the differences in the 2 schemes would be manifest in the children’s production of fractions commensurate with a given fraction. During the October 15 teaching episode, Jason independently produced how much 3/4 of 1/4 of a stick was of the whole stick as a novelty, and it was inferred that he engaged in recursive partitioning operations. An analogous inference could not be made for Laura. The primary difference in the 2 children during the teaching episodes was Laura’s dependency on Jason’s independent explanations or actions to engage in the actions that were needed for her to be successful in explaining why a fraction such as 1/3 was commensurate to, say, 4/12.