Current studies like PISA and TIMSS indicate that there is an alarming rate of German secondary school students who have severe mathematical difficulties. They only have very basal mathematical knowledge, which is hardly enough to successfully participate in the labour market. Current research found that a major requirement for secondary school algebra is the knowledge of basic concepts of mathematics. One of these concepts is the part-part-whole concept. In our study, we investigated to what extent this and subsequent concepts used in multiplication and division are available in the early grades of secondary school. 3,807 students from grades 5 to 7 solved various part-part-whole problems. Although performance increases from grade to grade, there are huge differences with regard to grades and the kind of school. Furthermore, there is a disturbingly high rate of students in 7th grade who still have only a very limited understanding of basic arithmetical concepts, especially in terms of division.