Maria Montessori was born in 1870 near Italy. She studied medicine in Rome, and after graduating became interested in the education of learning disabled children. As she moved through her career, she worked with children and applied methods that including using concrete materials like small slabs of wood used to train the eyes in the left to right reading motion, beads arranged to teach mathematics, and more. These materials seemed to deeply interest the children.
A large part of Montessori learning became independent work. The instructor would be there for support and guidance, but the student would mainly work through things on their own. This independent, self-guided exploration is a core tenant of the Montessori system.