Delta - now takes into account the subsequent corrections of the G8 curriculum in Bavaria and continues the series in the upper secondary level. The principles of the proven concept remain intact, but they have been further developed in important aspects: clear structure through the double-page principle; new: improved clarity by reducing page clutter; high-quality task culture; new: expanded offerings of simpler practice tasks; motivating, student-friendly design; new: optimized layout through a fundamental revision of the color concept; comprehensive, cumulative basic knowledge compendium in the appendix; new: streamlining of the volumes through self-test solutions.