The goal of this activity is close to the children's recent development area, and the key and difficult points are established accurately and concretely. In practice, many children line up according to the height of monkeys, some children line up from high to short, and some children line up from short to high. Some people line up according to the size of their hats, from big to small. Children can choose their favorite characteristics according to the different characteristics of monkeys. In the process of sorting, there are positive and negative sorting methods, but not every feature has positive and negative sorting. Guide children to learn actively in thinking and reasoning and establish mathematical concepts.