Maria Montessori devoted all her life to the development of learning materials and teaching methods. Montessori materials are sensory-based learning tools that are designed to isolate one skill or concept. The materials encourage hands-on learning, independent problem solving, and analytical thinking. Especially unique, is that each Montessori material is designed with a visual control of error. The codification of the materials stops with the elementary level ( even if the materials, especially for children with special need, can be well used till the seventh or eighth class). What happens afterwards? Maria Montessori tells to the adults to let the child unfold and develop his/her potential. She stresses the role of the teacher as someone who accompanies, almost serves, the children, the girls and the boys on their learning paths, in their development as human beings in respect of their nature, predispositions and skills. She believed in their possibility to become independent in their own way. The plan for the secondary school of Maria Montessori is called Children of the Earth and it is focused on the psycomotor, on the social and emotional and the cosmic (spiritual and scientific) education of the students. Their cognitive and intellectual development is in her view a natural result of the right activities that youngster performs. She thinks of the autonomy of the learner in his/her individual process and stresses the importance of observation and accompaniment of the student in the respect for his true nature, vocation, for his/her interests and skills. The interconnection among the subjects, the working and learning through projects and a problem- solving, analytical way of thinking, the huge space to imagination and aesthetical experiences ensures an integrated development of the personality of the student, of his/her physical, cognitive and intellectual abilities.