I'll teach you a way to find a good organization. There is a mathematical association in Shenzhen, and the cooperative organizations in the brochure attached to the Olympic Games textbook are all awesome. Bond is definitely the most famous in Shenzhen, but its teachers and management have fallen behind in recent years. Learning and thinking are ok, but the disadvantage is that there are a little more people in one class. After three hours of connection, the children don't receive well, which is a bit like the store bullying customers. I recommend Bai Ying Mathematics. They specialize in mathematics 10 years, with few advertisements. It has always been word-of-mouth publicity, but it is actually on the cooperation list. The teachers are very kind and caring.