In this paper we analyze the meanings of the "equal" sign as generated by sense production of the methods of substitution and comparison for solving problems and systems of equations of two unknowns. These methods are usually introduced through an extension process of the syntax and meanings recently learned by students in order to solve…

A longitudinal program evaluation approach used in the Vermont system of care for children and adolescents is described. The method focuses on movement between residential placements and compares system functioning to service system values using a person-level longitudinal database. This methodology can be useful in a number of fields. (SLD)

This article discusses issues in measuring lexical diversity, before outlining an approach based on mathematical modelling that produces a measure, D, designed to address these problems. The procedure for obtaining values for D directly from transcripts using software (vocd) is introduced, and then applied to thirty-two children from the Bristol…