Analisi fenomenografica dei risultati della sperimentazione di una proposta per l\'insegnamento dell'idrostatica nella scuola secondaria

In this paper a phenomenographic method, until now mostly used in behavioural and social sciences, is presented and a possible application to physics education research is discussed. the method was used to analyse results of questionnaires submitted to students (age 14-16) in order to evaluate the effectiveness of a teaching proposal on hydrostatics. The analysiswas performed with the aid of the computer program Ministep which implements the Rash model for measurements of students ability and item difficulty.