Children practice the “Duck and Cover” drill, to protect themselves against the effects of a nuclear explosion, 1950s
Duck and Cover is a method of personal protection against the effects of a nuclear explosion, which the United States government taught to generations of United States school children from the early 1950s until the end of the Cold War in the late 1980s. It was intended to protect them in the event of both an unexpected nuclear attack, which, they were told, might come at any time without warning and in the event sufficient warning is given.
Under the conditions of a surprise attack, immediately after they saw a flash they had to stop what they were doing and get on the ground under some cover—such as a table, or at least next to a wall—and assume a prone like position, lying face-down and covering their exposed skin and back of their heads with their clothes, or if no excess clothes such as a coat was available, to cover the back of their heads with their hands. Similar instructions were given in 1964 in the United Kingdom by Civil Defence Information Bulletin No. 5. and, in the 1980s, by the Protect and Survive series. Under the conditions where sufficient warning is given, they were told to find the nearest Civil Defense shelter, or if one could not be found, any well built building to stay and shelter in. From Wikipedia
A coal hole is a hatch in the pavement (sidewalk, in US usage) above an underground coal bunker. They are sometimes found outside houses that existed during the period when coal was widely used for domestic heating from the early 19th century to the middle 20th century.