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. "This Is Calculation C3 (Elementary Grade 3 Course)" helps children become faster and stronger at math. This workbook builds calculation skills through a 5-step learning system. Before starting calculation practice, children first build motivation and interest to prepare for self-directed learning, then learn the underlying principles behind each type of calculation. Once they understand the principles well enough, repeated practice helps them master the calculation process, and finally, solving a variety of problems helps improve accuracy.