Probably the best argument for maintaining such schools was not only the physical benefit derived, but the actual advance made by the children in their studies, although they spent less than half as much time on school work as did their companions in the regular schools, not only fully maintaining their standing, but ever surpassing their companions in the regular classes. Through results obtained from this first experiment in Charlottenburg came the resolve on the part of school authorities of other cities to inaugurate Open Air Schools in their respective localities, and in less than three years the movement had spread to England, where, in 1907, London opened her first school, modeled after that of Charlottenburg. The same remarkable results obtained during the first season here, as in the three years previously reported from Charlottenburg, awakened such popular enthusiasm that towns and cities in different parts of England began to plan for similar schools in the communities most needing them. Meanwhile, the movement spread to the United States. In 1908, one year after England had established her first Open Air School, this country opened its first Open Air School in Providence, Rhode Island. Although Providence has the distinction of priority in this matter, the school inaugurated by Providence was not, strictly speaking, the first Open Air School established on American territory, as a school of this type was opened in 1904 in San Juan, Porto Rico, by L. P. Ayres, now Associate Director of the Department of Hygiene of the Russell Sage Foundation, at that time Superintendent of Schools for Porto Rico. The San Juan school was an experiment. It was built to accommodate 100 children. It was simple in its arrangements; it had a floor and roof but no sides. Venetian blinds were provided to keep out rain and the too direct sunlight. The school was designed for children of no particular class, but was established in the endeavor to demonstrate that the regime which has proven beneficial for weak and ailing children will also benefit those that are strong and seemingly healthy. The results demonstrated fully the correctness of this idea. The children greatly preferred the outdoor classes, and even the teachers were most anxious to be assigned to outdoor work. Since then at least one more school of similar type has been opened in Porto Rico. Before showing what the United States has done in this very important movement, it might be interesting to learn how Germany and England have further developed their program, as the work done in these countries, particularly in Germany, served as the basis of the Open Air School movement in this country in the initial stages of its development.