The Montessori classroom is specifically designed to address the interests and abilities of children at each stage of development: infant/toddler, 3 to 6 years, 6 to 9 years, and 9 to 12 years old. It is a unique environment that fosters the development of order, concentration, coordination, and independence in a gentle atmosphere of respect, care, grace, and courtesy. The curriculum represents a continuum that builds on itself month by month and year after year, through providing materials and lessons that are developmentally appropriate for each age group. Children gain a deeper, more nuanced, and more integrated understanding over time, as well as adding knowledge and skills in all subject areas: practical life, sensorial, language, mathematics, science, history and cultural studies, geography, and the arts. At all ages the social, emotional, physical, and spiritual development of the child is an equally important part of the curriculum.