=Retardation and Knowledge Percentage.=--We said above, in estimating retardation, account should be taken of the course to which the pupil belongs--that is to say, the grade of instruction to which he has already attained. A child of nine years of age who has a retardation of three years has learned absolutely nothing; on the other hand, a child of twelve years who has a retardation of three years has learned something, since he has reached the intermediate course, first year. The difference between the two pupils is apparent; probably it will increase still more as years go on. To understand the matter clearly, it is necessary to compare the amount of retardation with the period of school attendance. The latter may be represented by the figure 100. Thus, our child of nine, who has learned nothing, has a retardation of three years in three years at school--that is to say, a percentage of 0; our child of twelve, who is in the "intermediate course, first year," has made in six years half the normal progress; he has therefore a "knowledge percentage" of 50. Such figures have evidently a quite different significance from those of the amount of retardation. Our opinion is that it suffices to make use of the simple calculation of retardation in selecting the defectives, for it is an easy and useful method; but when one is in the presence of a child, and desires to estimate his knowledge, not only for the actual moment, but with reference to his future and his capacity for learning, it is necessary to note also, and more especially, his "knowledge percentage." We suggest the following schedule to be filled up after the examination of the child: =Examination of Instruction of a Child proposed for Special Class.= Date of examination: Place of examination: Full name of pupil: Date of birth of pupil: This child has attended .......... school, ...... class. Attendance regular or irregular? Has he been able to follow his class? What is the amount of his retardation? _Reading._ (Syllabic, hesitating, fluent, expressive, intermediate--_e.g._, fluent-expressive.) Observations on reading: _Arithmetic._ The pupil can do the problems noted without mistake: (Refer to scale.) Observations on arithmetic: _Spelling._ Phrase dictated: Number of mistakes: _Conclusion._ Retardation in reading (taking account of school attendance): Retardation in arithmetic (_ibid._): Retardation in spelling (_ibid._): Knowledge percentage: Name and position of examiner: