Information about the series: Language plays a central role in the teaching of mathematical content. For children with a non-German native language or those needing additional 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 the educational standards in mathematics. To this end, eins-zwei-drei provides child-friendly language models, systematic development of mathematical vocabulary, clear explanation 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.