Section 2555 - Kindergartens, nursery and night schools1. The board of education of each city may maintain kindergartens which shall be free to resident children between the ages of four and six years, provided, however, such board may fix a higher minimum age for admission to such kindergartens.2. A board of education may maintain nursery schools which shall be free to resident children and may fix the age for admission.3. Night schools, which shall be free to all persons residing in the city, and wherein the common branches and such additional subjects as may be adapted to students applying for instruction are taught on at least two nights each week, for two hours each night, shall be maintained by the board of education on at least one hundred nights.