Description ① A 5-step learning process: Preparation → Principle → Mastery → Speed → Accuracy ② A self-directed learning system that helps children understand calculation principles and methods on their own Becoming faster and stronger, 'This Is Calculation C4 (Elementary 3rd Grade Course)' is a workbook designed to improve calculation skills through a 5-step learning system. Before starting calculation practice, children first build interest and motivation to develop a self-directed learning attitude. They then learn the underlying principles behind each calculation topic — understanding why it works the way it does. Through repeated practice, they master the calculation process, and finally, by solving a variety of problem types, they improve accuracy and confidence.