This is a global problem. Children are lively by nature and easily distracted. Guide them to improve their attention, give him some math games, and let him learn to do it with his classmates. When others can't do it, his self-confidence will be improved. The key is to make him feel that solving a math problem that others can't solve is something that his friends admire. If he finds the feeling, things will be easy. The higher the complexity of mathematics, the more it relies on computer software to assist calculation in universities. To solve long-term problems, cram schools are really weak. The third grade of primary school is still far from the rebellious period. Remember that encouragement is more than criticism.