Children: 2-4 years old, middle class children: 5-8 years old, large class children: 9- 12 years old.

Two-and-a-half to three-and-a-half years old is the key age to teach children to behave themselves, so that they can develop good hygiene habits and the habit of observing the work and rest system. Before the age of 4, it is the key age for the development of image vision. 4 ~ 5 years old is the key period to start learning written language. About 5 years old is the key age to master mathematical concepts, and it is also the second key period for children's oral development. 5 ~ 6 years old is the key period to master language vocabulary ability. 6 ~ 12 years old is the golden age for shaping children's psychological development.

Extended data:

pay attention to the diet

1, choice of staple food and beans:

Japonica rice, indica rice, purple rice, wheat flour, oats, mung beans, adzuki beans, black beans, tofu, rice, millet, oats, buckwheat, soybeans and their products.

2, the choice of meat, eggs, milk:

Lean pork, ribs, beef, chicken, duck, pork liver, crucian carp, hairtail, eel, loach, shrimp, shrimp skin, eggs, mutton, yellow croaker, oyster, milk, etc.

3, the choice of vegetables:

Carrots, potatoes, spinach, Chinese cabbage, green peppers, pumpkins, cucumbers, bean sprouts, kelp, auricularia, sweet potatoes, tomatoes, vegetables, onions, celery, cauliflower, mushrooms, laver and bamboo shoots.

4, the choice of fruit:

Apples, bananas, oranges, watermelons, peaches, cantaloupes, mangoes, pitaya, kiwis, pineapples, strawberries, pears, etc.

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