New national curricula and another perspective on mathematics education like for example in the New Math in the 1960th make textbooks change. Thereby, not only the mathematical content differs, even more the presentation and handling of mathematics show great varieties. To identify and explore such differences with statistical methods, a category system for analysing textbooks was developed. By now 30 000 data sets of 14 textbooks are collected. Thereby, first assumptions about differences and changes were made.