be recognized that below these two groups of retardates are found children whose social incompetence and lack of understanding will necessitate longtime or permanent care within their own homes or in suitable institutions. These children have little or no competence for training directed toward social acceptance or occupational usefulness and would therefore not fit into the school programs described in this bulletin.

The moderately mentally retarded pupils for whom many school districts maintain special education services frequently have been designated in terms of intelligence quotients. The range between 50 and 75 is probably most often used, although variations in admission standards are often found. In view of present tendencies to accept qualitative rather than quantitative interpretations of mental examination results, admissions to special classes cannot be based upon rigid IQ classifications. At the upper limits of eligibility there will be found children with comparable test scores, some of whom need the advantages of special class placements and others who seem to function well in regular class groups. Likewise, at the lower limitations some children may make satisfactory progress in a special class for educable children while others prove to have little competence for either social or scholastic achievement. The prognosis of educability depends upon a number of interrelated factors, the mental test score representing at best a measurement of general intellectual performance at the time of the examination. Factors of cultural background, social development, speech deficiencies, physical abnormalties, and emotional conflict must be considered in the total clinical evalution-an evaluation that is valid only when it is based upon adequate data and interpretation by qualified psychologists.

The determination of who would profit by placement in classes for more severely retarded children similarly must be based upon many factors in addition to test scores. It is probable that the majority of the children assigned to these groups will measure in the IQ brackets below 50 to 55, but how far down the IQ scale the severely retarded child can measure and still profit from the program is relatively unimportant. The important considerations are whether or not the child has indicated potentialities for social adjustment, speech development, following directions, and caring for his own needs to the extent that, with further training, he may be able to live in a family group and contribute some useful activity in his home or the community.

Distinguishing between those children who are potentially trainable and those who need long-time care presents even more involved considerations. There seems to be little evidence that any certain IQ is basic to successful achievement in training programs. At least one school system has found it necessary to change its standards of admission to classes for the severely retarded because of the unreliability of intelligence quotients as predictors of successful achievement. Some schools have preferred to set up only

general criteria for admission, including the abilities to exercise personal control, to communicate, and to respond to directions. The Houston, Tex., classes accept on a trial basis all children who possess these abilities, and they are allowed to remain as long as sufficient progress is observed. For many children near the borderline of acceptability, classes for the severely retarded may need to offer a period of trial placement and diagnostic instruction. In some instances only adequate observation under optimum conditions will enable the educator and psychologist to determine the pupils' actual potentials for training and eventual adjustment.

The tendency to accept a functional differentiation between the candidate for ordinary special class services and the child who is acceptable only in groups for the more severely retarded is illustrated in the terminology used in a modification of the California school law. The Code of 1949 established special classes for children who "are incapable of being educated profitably and efficiently through ordinary classroom instruction" but "who may be expected to benefit from special education facilities designed to make them economically useful and socially adjusted." These are the children who are often considered to be educable. A recent amendment authorized an extension of these facilities for the training of more severely retarded pupils "who may be expected to benefit from special education facilities designed to educate and train them to further their individual acceptance, social adjustment, and economic usefulness in their homes and within a sheltered environment." The terminology used in the California Code parallels, to a great extent, the description found in the Encyclopedia of Educational Research. Similar differentiations are stated in a recent modification of the Minnesota school laws relating to mentally retarded children. The interpretations are obviously left to the school psychologists who will examine and diagnose the candidates for special class placements.

How Many Severely Retarded

Children Are There?

Authorities in the field of special education 7 have estimated that from 2 to 3 percent of the school population is mentally retarded to the extent that special education services are necessary for the pupils' educational welfare. The Encyclopedia of Educational Research indicates that this proportion may be as high as 4 or 5 percent.

8

Since this bulletin assumes that special education services for moderately retarded pupils are accepted in principle as an obligation of the public schools, 9 the important question at the moment concerns the number of severely mentally retarded children for whom additional training classes may be established.

Unfortunately the only existing data from which any conclusions may be drawn are the distributions of intelligence test scores compiled upon large samplings of the population. Merrill, 10 in standardizing the Revised Stanford-Binet scale, reported than .23 percent of her more than 2,900 subjects fell in the IQ intervals between 30 and 49. For various reasons this percentage cannot be regarded as representative of the true incidence of severe retardation as it is interpreted in this bulletin. It has already been pointed out that the use of the IQ alone to determine the degree of retardation or potential for learning is unrealistic. It is quite probable that some children with measurable IQ's above 50 will need to be considered for placement in classes for severely retarded children rather than in the regular special classes now in existence. Also, it has been observed that there seems to be no information that would indicate how far down the IQ scale a retarded child can measure and still possess competence for trainability. Furthermore, it is doubtful if the methods of selection employed in obtaining the subjects for the current studies of IQ's for large population groups insured an adequate sampling at the extreme lower levels of mental ability. Since it is also known that both brain injuries and other physiological factors frequently seem to contribute to the incidence of the more

7 For instance, see White House Conference on Child Health and Protection. Special Education: The Handicapped and Gifted. New York, Century Co., 1931; Berry, Charles Scott. Public School: Education of Mentally Retarded Children. Columbus, Ohio, Ohio State University Press, 1933; Martens, Elise H. Curriculum Adjustments for the Mentally Retarded. Washington, U. S. Government Printing Office, 1950. Federal Security Agency, (Office of Education, Bulletin 1950, No. 2.)

Encyclopedia of Educational Research. (Rev. Ed.) New York, The MacMillan Co., 1950. p. 729. 34 States have provided for this type of education through legal enactments with and without financial assistance.

10 Merrill, Maude A. The Significance of IQ's on the Revised Stanford-Binet Scales. Journal of Educational Psychology, 29: 641-51, December 1938.

severe degrees of mental deficiency, it is probable that the curve of distribution of intelligence may be rather heavily weighted at the lower intervals, as compared with normal-curve expectations.

It seems obvious that the percentage of children who might profit from training programs may be somewhat higher than the 0.23 of 1 percent found by Merrill in the IQ intervals between 30 and 49, but it appears equally doubtful that the percentage will ordinarily rise above one-half of 1 percent, except under unusual circumstances in local communities or restricted areas. In view of the inadequacy of available data, this percentage must be considered as no better than a rough estimate. Adequate community surveys, based upon more complete samplings of the population and improved diagnostic procedures, would be necessary if statistically valid estimates were to be obtained. Until such data are available, it may be necessary to accept this percentage as a basis for planning services for severely retarded, but trainable, children.

In 1950, children between 5 and 18 years of age constituted approximately one-fifth of the total population. Therefore, the incidence of severely retarded children of school age who might be served by training facilities should not be more than one per thousand persons in the general population. In terms of population statistics, cities of 10,000 might expect to include a maximum of 10 severely retarded children, some of whom will necessarily be enrolled in private and institutional schools; similarly, a maximum of 100 severely retarded children might be found in a general population of 100,000. It would seem unlikely, therefore, that school districts serving less than 10,000 total population would find enough severely retarded children to justify the provision of special training facilities unless services were maintained on a multiple district basis.

What Type of Program Is Needed

For The Severely Retarded Child?

PURPOSES AND OBJECTIVES

One purpose for maintaining special classes for moderately retarded children is to afford those pupils who cannot profit from the general educational program opportunities to develop self-independence and vocational competence. However, the purposes for establishing classes for the more severely retarded trainable child may be somewhat more involved, excluding considerations of economy and unavailability of institutional school space. Nevertheless, they may be summarized in the following manner:

1. While a very small percentage of the more severely retarded group, even under optimum training conditions, may be able to achieve a limited degree of self-direction (and a few may be able to participate in sheltered workshop activities when these are available), a larger number will achieve a moderate degree of personal and social development and become economically useful in their own homes. For these children the class will provide training experiences that will enable them to develop to the fullest extent possible the limited abilities which they possess..

2. Lack of responsiveness because of severe conflicts, social immaturity, physical involvements, or speech retardation may result in inadequate measurements of intellectual ability and influence the examiner to reserve his judgment relative to the potentials of a number of mentally retarded children. These children may respond more adequately to repeated testing procedures after effective socializing experiences have been provided. A few may eventually become candidates for the regular special class groups for educable children. For such children the training class may afford opportunities for observation and further study. This is one of the services rendered by the pre-special classes maintained by the Detroit Public Schools (see p. 36).

3. Another purpose of the class for the severely mentally retarded will necessarily involve its screening functions, for not all of the children assigned on the basis of initial tests and preliminary observations will prove capable of training and personal adjustment in a public-school situation. Only observation over an extended period during which stimulating experiences are provided will allow the teacher and psychologist to render an adequate evaluation of certain pupils' potentials for training. Undoubtedly, a substantial number of the children referred for training-class placement will require eventual institutional care. A corollary of this purpose is that the training class must provide opportunities for the counseling of parents in regard to institutional placements in those instances in which pupils do not indicate the necessary capacity for growth and development. This will be discussed at greater length in a subsequent section, but it is important to recognize that the purposes of the training class go beyond what it can offer the pupil and extend to the needs of parents for understanding and guidance.