Bias of item and ability in fractions

Abstract

We observe the main concepts about Item Response Theory (IRT): Item characteristic curves, the new meaning of discrimination and ability curves. We apply this ideas to the study of cognitive ability levels with the learning of fractions in elementary school in Spain. The designs showing better than the classic systems the differences between courses (5-8 EGB) and some other ineresting characteristics about the Onslow-Kieren's ideas.