​The primary school De Regenboog is located in the polder of Slikkerveer, part of the municipality of Ridderkerk, and has grown along with the expansion of this post-war residential district. The original building by architect Leo Oskam is a valuable example of modernist school architecture. The free-standing wings followed the urbanism of L-shaped slabs floating on green islands. The typology followed the system of the ‘portiekschool’: stacked classrooms separated by bays of staircases, an efficient building system closely related to the typology of surrounding apartment buildings.