We shall have occasion to emphasize over and over again the fact that it is the use of information and not the gathering of information that improves the health. The United States Weather Bureau saves millions of dollars annually, not because flags are raised and bulletins issued foretelling the weather, but because shipowners, sailors, farmers, and fruit growers obey the warnings. Mere examination of school children does little good. The child does not breathe better or see better because the school physician fills out a card stating that there is something wrong with his eyes, nose, and tonsils. The examination tells where the need is, what children should have special attention, what parents need to be warned as to the condition of the child, what home conditions need to be corrected. If the facts are not used, that is an argument not against obtaining facts but against disregarding them. In understanding medical examination we should keep clearly in mind the distinction between medical school inspection, medical school examination, and medical treatment at school. Medical inspection is the search for communicable disease. The results of medical inspection, therefore, furnish an index to the presence of communicable diseases in the community. Medical examination is the search for physical defects, some of which furnish the soil for contagion. Its results are an index not only to contagion but to conditions that favor contagion by producing or aggravating physical defects and by reducing vitality. Medical treatment at school refers to steps taken under the school roof, or by school funds, to remove the defects or check the infection brought to light by medical inspection and medical examination. Treatment is not an index. In separate chapters are given the reasons for and against trying to treat at school symptoms of causes that exist outside of school. When, how often, and by whom inspection and examination should be made is also discussed later. The one point of this chapter is this: if we really want to know where in our community health rights are endangered, the shortest cut to the largest number of dangers is the physical examination of children at school,--private, parochial, reformatory, public, high, college.