Description ① A 5-step learning process: Preparation → Principle → Mastery → Speed → Accuracy ② A self-directed learning system that helps children discover the principles and methods of calculation on their own "This Is Calculation C1 (3rd Grade Level)" — Getting Faster and Stronger. This workbook uses a 5-step calculation learning system to strengthen your child's math skills. Before beginning calculation practice, children first build self-directed learning habits by sparking interest and motivation. Then they learn the underlying principles behind each calculation topic — understanding why it works the way it does. Once they've mastered the principle through repeated practice, they move on to solving a variety of problems designed to improve accuracy and overall calculation skill.