Parameters, unknowns and variables: a little difference?

In this paper we report on a research concerning algebra learning in secondary school; the focus is on parameters and their relation to unknowns and variables. In developing our study we at first analysed the notion (in its manipulative and conceptual aspects) using a methodology we had already tested in other studies on algebra learning which consists in singling out what lies behind to a given notion and in constructing a tree of notions related to the initial one. We then prepared a questionnaire to establish how students perceive the differences between parameters, unknowns and variables and deal with algebraic situations where these notions intervene. The questionnaire was handed out to 199 students aged 16-17 of 3 schools. The results offer us useful insights for the analysis of fundamental aspects of algebraic thinking.