A data model explicitly determines the structure of data. Data models are specified in a data modeling notation, which is often graphical in form. A data model can be sometimes referred to as a data structure, especially in the context of programming languages. Data models are often complemented by function models, especially in the context of enterprise models.
The Association Montessori Internationale (AMI), founded by Maria Montessori in 1929, maintains Montessori educational principles and disseminates Montessori education throughout the world.
Public school districts in the U.S. began experimenting with Montessori classrooms in the mid 1970s in Arlington, Virginia; Philadelphia; Reading, Ohio; and San Mateo, California. By the mid-1980s there were about 50 sites.