The basis is to accurately and skillfully distinguish the face value, because the problem of some children in the practice process is that they can't recognize the face value. Then use the learning tool to make a simple conversion, from 20 points, 50 points, and then to the equivalent exchange of one dollar, following the principle of from shallow to deep, from simple to complex. The key is to have hands-on experience. Parents can accompany them in life, so that children can conduct small transactions by themselves, which can not only arouse their enthusiasm, but also actively explore knowledge. In a word, practical operation is the best way to learn.