Montessori believed that a child’s mind is mathematical and based on the order of perceptual awareness found in the development of the senses. She designed “hands-on” materials to help the child investigate, calculate, measure, imagine and create. The acquisition of mathematical principles is seen as developing logically from concrete to abstract, and from simple to complex. Montessori Math includes the development of concepts such as numeration, place value, fractions, and the basic operations of addition, subtraction, multiplication, and division using numbers up to 9999 which are experienced and learned using concrete manipulative materials.