In the early years of the 20th century, tuberculosis ravaged American cities, taking a particular and often fatal toll on the poor and the young. In 1907, two Rhode Island doctors, Mary Packard and Ellen Stone, had an idea for mitigating transmission among children. Following education trends in Germany, they proposed the creation of an open-air schoolroom. Within a matter of months, the floor of an empty brick building in Providence was converted into a space with ceiling-height windows on every side, kept open at nearly all times.