Childhood is from 2 years old to 12 years old, which Rousseau called rational sleep period. Children's words and deeds in childhood are dominated by sensibility and lack rational power. Therefore, children should not be educated directly during this period. The task of education is to develop children's external sensory organs. Because external sensory organs are the premise of intellectual education.

Rousseau believes that in order to develop external sensory organs, children should be given opportunities for various activities as much as possible; For the sense of touch, let children touch and grasp everything in person, play games in the dark, and let children understand the relationship between feelings and things that cause feelings; In order to develop eyesight, children should learn sketching and painting as soon as possible; In order to develop listening, Rousseau advocated that children should practice singing, pay attention to pure and clear pronunciation, and get used to listening to rhythmic and melodic sounds; Regarding children's sense of taste and smell, Rousseau thinks that children's food should be natural and simple. Rousseau is the first person in the history of western education to study the education of children's external sensory organs in detail, which has a great influence on the development of preschool education later.