This book offers prospective teachers during their training, students during their internships, and practicing educators a variety of suggestions for planning and implementing their mathematics lessons. The theoretical foundations of the principles of modern mathematics instruction, as well as the planning and design of lesson observations, are practically applied through 18 authentic, carefully selected lesson plans that form the core of the book. These lesson plans provide a clear overview of the current requirements and objectives of elementary school mathematics instruction by covering many general and content-related mathematical competencies in line with educational standards. Therefore, the planning can easily be adapted to many other lessons.