Disadvantages: Improper learning methods may lead to students' dislike of mathematics. After all, students have little free time and are often occupied by various classes. Moreover, some students abuse the knowledge and skills of Olympic Mathematics, and then "make a fuss" about simple problems, without learning to use them flexibly, which interferes with their normal study. This example is not without it.
Suggestion: Ask your child's interest in Olympic Mathematics, and carefully protect his interest in mathematics. You don't have to take an Olympic Mathematics class. You can read more relevant extracurricular books while learning the classroom knowledge well. With a certain accumulation, it is not a problem to teach the course of Olympic Mathematics by yourself. However, if you want to get a place in the national competition, you must find a coach in high school, not in primary school.