<P> For Thomas, the groups themselves had to reinscribe and reconstruct themselves to prosper . Burgess studied the history of development and concluded that the city had not grown at the edges . Although the presence of Lake Michigan prevented the complete encirclement, he postulated that all major cities would be formed by radial expansion from the center in concentric rings which he described as zones, i.e. the business area in the center, the slum area (called the zone in transition and studied by Wirth: 1928, Zorbaugh: 1929, and Suttles: 1968) around the central area, the zone of workingmen's homes farther out, the residential area beyond this zone, and then the bungalow section and the commuter's zone on the periphery . Under the influence of Albion Small, the research at the School mined the mass of official data including census reports, housing / welfare records and crime figures, and related the data spatially to different geographical areas of the city . Shaw and McKay created maps: </P> <Ul> <Li> spot maps to demonstrate the location of a range of social problems with a primary focus on juvenile delinquency; </Li> <Li> rate maps which divided the city into block of one square mile and showed the population by age, gender, ethnicity, etc.; </Li> <Li> zone maps which demonstrated that the major problems were clustered in the city center . </Li> </Ul> <Li> spot maps to demonstrate the location of a range of social problems with a primary focus on juvenile delinquency; </Li> <Li> rate maps which divided the city into block of one square mile and showed the population by age, gender, ethnicity, etc.; </Li>

Identify the key tenets of the chicago school in american sociology