General term for a range of programs for pre-kindergarten children, generally from ages two or three to five; sometimes used synonymously with early childhood education. Although the term does not cover informal play groups, preschool refers to any group or class organized for educational experience for children before they enter elementary school (either in kindergarten or first grade). That includes nursery schools, schools following the Montessori method, Head Start programs, and similar schools that are not established as part of a graded system in a school.