This article illustrates the use of an explanatory item response modeling (EIRM) approach in the context of measuring group differences in science achievement. The distinction between item response models and EIRMs, recently elaborated by De Boeck and Wilson (2004), is presented within the statistical framework of generalized linear mixed models.…

Presented are the results of an analysis of the cognitive stages of tenth-grade pupils using a six-week unit on the respiratory system. The research design, instruments, and data analysis are discussed. A variety of cognitive levels was found and may be related to learning outcomes. (CW)

French tenth grade physics classes were observed as they studied electric circuits over a one-year period. An analysis is presented of tests taken during the year. The main point separating "average" students from "good" ones is their performances in "implicitly difficult exercises," that is, in what appears…