Abstract
The paper first discusses the dilemma that, due to the hierarchical order of arithmetic content, substantial content-related participation in inclusive classrooms will become increasingly difficult over the years if mathematics instruction does not succeed in imparting basic knowledge and skills such as part-whole understanding of numbers and adding and subtracting without counting, and this at an early stage. Against this background, an individual case study is reported. The girl in question started school with a very limited set of prerequisites for the learning of arithmetic. By the end of Year 1, she had made considerable progress, but the study suggests that this was greatly facilitated, if not made possible, by the massive additional support of a second teacher, which is extremely rare in South Tyrol, Italy, where the girl lives. The implications of this for the school organisational framework required for inclusion are discussed.