Infant and Toddler Programs: Montessori classrooms for children under three fall into several categories, with a number of terms being used. A "Nido", Italian for "nest", serves a small number of children from around two months to around fourteen months, or when the child is confidently walking. A "Young Child Community" serves a larger number of children from around one year to two-and-a-half or three years old. Both environments emphasize materials and activities scaled to the children's size and abilities, opportunities to develop movement, and activities to develop independence. Development of independence in toileting is typically emphasized as well. Some schools also offer "Parent-Infant" classes, in which parents participate with their very young children.
Preschool and kindergarten: Montessori classrooms for children from two-and-a-half or three to six years old are often called Children's Houses, after Montessori's first school, the Casa dei Bambini in Rome in 1906. This level is also called "Primary". A typical classroom serves 20 to 30 children in mixed-age groups, staffed by one trained teacher and an assistant. Classrooms are usually outfitted with child-sized tables and chairs arranged singly or in small clusters, with classroom materials on child-height shelves throughout the room. Activities are for the most part initially presented by the teacher, after which they may be chosen more or less freely by the children as interest dictates. Classroom materials usually include activities for engaging in practical skills such as pouring and spooning, materials for the development of the senses, math materials, language materials, music and art materials, and more.
Elementary Classrooms: Classrooms for this age are usually referred to as "Elementary", and can range in size from very small up to 30 or more children, typically staffed by a trained teacher and one or more assistants. Classes usually serve mixed-age six- to nine-year old and nine- to twelve-year old groupings, although six- to twelve-year old groups are also used. Lessons are typically presented to small groups of children, who are then free to follow up with independent work of their own as interest and personal responsibility dictate. The scope of lessons and work in the Elementary classroom is quite broad. Montessori used the term "cosmic education" to indicate both the universal scope of lessons to be presented, and the idea that education in the second plane should help the child realize the human role in the interdependent functioning of the universe. Classroom materials and lessons include work in language, mathematics, history, the sciences, the arts, and much more. Student directed explorations of resources outside the classroom, known as "going out" in Montessori, are an integral element of the Elementary work.