Hello, mathematics is a complex science, it must be studied consistently and competently. It requires deliberate approaches in the study of each topic, understanding each lesson. Mathematics for the fourth grade is best learned by a student with an independent desire to understand new material and thoughtful reading of the lessons presented. So the student begins to discipline himself, which has a beneficial effect on the personality in the future. If the student did not immediately master the material covered, there is no need to be upset, you need to be persistent in achieving the goal, read, try again and again. By the way, there are special free math websites for math kids for this, where your child can study this subject in more depth.