Maria Montessori, a physician, psychologist, and anthropologist, developed her approach to education through scientific observation. In her study of children she saw how they interacted with one another, were able to learn through the very specific and scientific materials that she provided for them and how children move through very specific stages of development. Her study of children brought her to countries all over the world where she also observed that the stages of development were universal to all children. Dr. Montessori opened the first Montessori school in 1907. Through her work she discovered that children learn best through hands-on experience. She designated an extensive collection of materials that allow children to experience concepts in a very concrete way, beginning at a very sensorial level, becoming increasingly abstract as the children's understanding grows. Once presented with these materials and given the freedom to explore them, she found that children will choose work appropriate to their needs. Today, there are Montessori schools in nearly every country throughout the world.