Information about the series: Language plays a central role in conveying mathematical content. For children with a non-German native language or those in need of enhanced language support, this often lies at the root of seemingly mathematical problems. In conjunction with the article system (der-die-das), eins-zwei-drei responds consistently to this issue as the first teaching material: It combines mathematical subject content with systematic language support, ensuring that all children can meet educational standards in mathematics. To achieve this, eins-zwei-drei offers child-friendly language models, systematic development of mathematical vocabulary, clear explanatory phases for introducing new content, carefully formulated mathematical tasks that take linguistic stumbling blocks into account, extensive information on these stumbling blocks, and practical teaching suggestions in the teacher's materials.