Description Week 1 - Adding 2, 3, 4 Week 2 - Adding 9, 8 Week 3 - Adding 7, 6 Week 4 - Challenge! Calculation King Week 5 - Adding 5 Week 6 - Challenge! Calculation King Math Starts with Principles Math is an abstract discipline that expresses relationships between concrete objects through the agreed-upon language of numbers and symbols. This is the biggest reason children find math difficult. Math can only show its true power when it comes with proper understanding. At every stage, principles matter most in math. Changes in Math Education The era where simply knowing how to get an answer was enough is coming to an end. Rather than repeating a single method for calculations, it's important to understand a variety of solving methods. Textbooks teach why things work the way they do and encourage students to think of multiple approaches, but students often forget the underlying principles through simple repetitive practice, mechanically producing answers without fully understanding how to apply what they've learned. Consistent practice with calculations, organized into 4 to 6 books according to each learning stage from preschool through elementary school, allows children to study steadily for just 10 minutes a day. Learning principles and various methods is made enjoyable through illustrations, practice is varied, and the concluding sections are designed for focused review. With a manageable daily study load, children will find their calculation skills have noticeably improved before they know it. The revised edition of Wonli Sem expands video lectures and strengthens the principle-based learning process for upper elementary grades, making it easier to understand principles, concepts, and calculation methods, while reinforcing practice for a more complete learning experience. We hope Wonli Sem helps resolve parents' concerns about their children's math calculation skills.