The article highlights the principles of Montessori pedagogy that places the full respect of the child's freedom of expression and manifestation in the center of education. Particular attention is paid to the observation of the child under the conditions of its free manifestation. The results of Maria Montessori's work with normal children and disabled children are analyzed, which are based on the experience of the French doctor, Itard and the teacher and doctor Edouard Seguin. A special emphasis is placed on the environment and materials of a Montessori class, where children have a great freedom of expression, a great freedom of movement, which causes them to reveal their needs and skills.