It is important to put homework materials in the math activity area. Operating materials are the media of education, the tools to help children systematically construct mathematical knowledge and induce them to explore and learn actively, and the material pillars applied to operating actions, so that external material actions gradually evolve into internal conceptual actions. Providing materials is not only the preparation before activities, but also an important means to guide children to learn mathematics knowledge and develop their thinking ability in the whole education process. Therefore, the cognitive characteristics of children of all ages should be fully considered when providing homework materials. For example, children in small classes are good at imitating in the cognitive process, with poor learning purpose and weak sense of task. They are interested in moving tools and using them. However, in large classes, their learning objectives have been enhanced, they can work hard to complete their learning tasks and attach importance to learning results and evaluation. The cognitive characteristics of small classes and large classes are different, and the effects of the same materials are completely different. A teacher in a large class used the seal and the composition of physical exercise once, and the effect was very good. A small class teacher imitated this form, and provided the children with a bird's seal behind two birds in the small class number formation activity, which was 3 birds, and 2 plus 1 was 3. When the children printed the seal on the paper, a bird flew from behind at once, and the children were very excited. They printed on their faces and hands. The teacher was very angry and thought that the child was deliberately naughty. In fact, it is the teacher's lack of research on the learning characteristics of children in this class and improper materials. In the math activity area of middle and large classes, there must be clear tasks and requirements, otherwise children are not interested. Therefore, it is necessary to integrate learning tasks into materials, such as adding some worksheets and other materials. Children will be interested in operating according to the requirements of the worksheet and cooperating with the real thing. In the activities, they can not only get the practice of relevant knowledge, but also cultivate a sense of task, thus gaining the satisfaction of success and enhancing their self-confidence. Therefore, we should pay attention to the cognitive characteristics of children at all stages when putting in materials.