Piaget divides children's cognitive development from birth to 15 years old into four stages: perceptual motor stage (0-2 years old), pre-operation stage (2-7 years old), specific operation stage (7- 12 years old) and formal operation stage (12 ~ 15 years old).

Piaget found that children (2-7 years old) in the pre-operation stage often cannot form conservation, and their thinking has two basic characteristics: one-sidedness and lack of reversibility. One-sidedness means focusing on one aspect of an object and ignoring other aspects. Lack of reversibility means paying attention to the state of things and ignoring the transformation process of things.

The research on the conservation of children is one of the topics studied by psychologists in the world, and there are also some studies in China. For example, in 1987, Morey conducted a training study on children's length conservation from four and a half years old to five and a half years old, and thought that training children's length conservation by activity internalization could effectively promote the formation of children's length conservation schema.

At the end of the big class, Zhou Xin tracked the mathematical cognitive development level of six classes 149 children in two kindergartens, and found that Piaget's concept of quantity conservation could not be developed until children were 7 years old, and more than half of the children's concept of quantity conservation had yet to be developed.

This study intends to study the development level of number conservation and length conservation of 150 children in Wenzhou, aiming at determining the development level and formation of number conservation and length conservation of children in different ages, so as to further reveal the development characteristics of child conservation in the new period. Generally speaking, the formation of children's number conservation and length conservation needs a development process, and children of all ages have their own development characteristics.

This study shows that children at different ages have different levels of development of number conservation and length conservation. With the growth of age, the level of child care is really developing. This study also shows that the number conservation of children is formed earlier than the length conservation. Piaget pointed out the imbalance of children's conservation development and determined the order of the formation of each conservation, in which the number conservation age is 0 ~ 7 years old and the long conservation age is 0 ~ 1 1 year old.

The results of this study are basically consistent with Piaget's conclusion, but the age of children's number conservation is a little earlier. Piaget believes: "As the most obvious indicator in the pre-operation stage, children have no concept of conservation before the age of seven or eight." This study found that the initial number of children was conserved at the age of 56, which was earlier than Piaget's conclusion 12 years.

In addition, the development of children's number conservation and length conservation follows the development law of children's thinking stage, that is, the order of intuitive action thinking-concrete image thinking-abstract logical thinking. This study proves that the development of number conservation and long conservation has age stages and is a continuous development process, and the development of conservation is influenced by different factors.

Individual differences in child care are obvious, which are related to parents' educational level, emphasis on education and the quality of kindergarten education. Parents' educational level and emphasis on education have a great influence on the formation of children's self-restraint. Although parents don't directly teach their children the method of conservation, the children's thinking level is obviously related to the formation of conservation.

In addition, kindergartens with poor education quality tend to be "primary school". These kindergartens often only attach importance to imparting knowledge, but neglect the cultivation of children's thinking ability. For example, this study found that the formation of number conservation is influenced by children's sense of number, that is, the so-called sense of number can quickly and accurately identify the number of small sets through vision.

There are age differences in the development of number sense ability, and children with poor number sense ability often need to rely on counting methods or strategies instead of visual observation. In this study, large-class children have a certain sense of numbers, which is positively related to their regular kindergarten education with quality assurance.

Suggestion 1. Education should adapt to the development of young children. Children's number conservation and length conservation did not occur in advance, indicating that the development of children's thinking depends on their physiological maturity. Improper elevation will only make children mature prematurely, and the fragile foundation cannot provide enough support for their future development.

Therefore, education should adapt to children's development level, guide children's development on the basis of their physical maturity, respect children's development laws, and find a reasonable balance between educational goals and development possibilities.

Second, we should pay attention to cultivating children's thinking ability. Kindergarten and family education should not take imparting knowledge and skills as the primary purpose of education, while ignoring the cultivation of children's thinking quality and ability. It is better to teach people to fish than to teach them to fish. Thinking ability is one of the essential qualities of future talents, and it is also an important basis for testing children's intelligence level. Cultivating children's thinking ability from an early age is extremely important for their healthy growth.

Recommendation 3: Education should promote the development of young children. Vygotsky's theory of "zone of proximal development" emphasizes that teaching should be ahead of development, which is the best period for teaching. The survey found that middle-class children can make correct judgments with proper guidance from teachers. It can be seen that proper teaching can help children master the concept of conservation earlier and promote the development of their thinking.

In a word, the formation of children's number conservation and length conservation is an important part of children's thinking development, and studying children's conservation development is an important way to reveal the laws and characteristics of children's thinking development.