This document details the Montessori approach to educating children from age 3 through age 12. Section 1 provides an introduction to Montessori and its history, focusing on Maria Montessori's work, the Montessori educational philosophy, educational practices (including multi-age grouping and teaching methods, Montessori teachers and their training, educational materials, the use of television and computers as educational tools, and Montessori at home). Section 2 describes parenting and teaching children in different age groups, while section 3 presents information on preparing the environment. Sections 4 through 12 detail the following aspects of the Montessori approach for children ages 3 to 6 years: family life, toys and games, earth, plants and animals, people, language, music, art, and mathematics. Sections 13 through 19 detail the following areas of the Montessori approach for students ages 6 to 12 years: family, earth, plants and animals, history, geography, and biography; language; the arts; and geometry, mathematics, and invention. Section 20 describes the Montessori approach for students from 12 to 18 years, focusing on the Erdkinder. (KB)