THE INTELLIGENCE OF RETARDED CHILDREN USUALLY OVERESTIMATED. One of the most common errors made by the teacher is to overestimate the intelligence of the over-age pupil. This is because she fails to take account of age differences and estimates intelligence on the basis of the child's school performance in the grade where he happens to be located. She tends to overlook the fact that quality of school work is no index of intelligence unless age is taken into account. The question should be, not, "Is this child doing his school work well?" but rather, "In what school grade should a child of this age be able to do satisfactory work?" A high-grade imbecile may do average work in the first grade, and a high-grade moron average work in the third or fourth grade, provided only they are sufficiently over-age for the grade in question. Our experience in testing children for segregation in special classes has time and again brought this fallacy of teachers to our attention. We have often found one or more feeble-minded children in a class after the teacher had confidently asserted that there was not a single exceptionally dull child present. In every case where there has been opportunity to follow the later school progress of such a child the validity of the intelligence test has been fully confirmed. The following are typical examples of the neglect of teachers to take the age factor into account when estimating the intelligence of the over-age child:-- _A. R. Girl, age 11; in low second grade._ She was able to do the work of this grade, not well, but passably. The teacher's judgment as to this child's intelligence was "dull but not defective." What the teacher overlooked was the fact that she had judged the child by a 7-year standard, and that, instead of only being able to do the work of the second grade indifferently, a child of this age should have been equal to the work of the fifth grade. In reality, A. R. is definitely feeble-minded. Although she is from a home of average culture, is 11 years old, and has attended school five years, she has barely the intelligence of the average child of six years. _D. C. Boy, age 17; in fifth grade._ His teacher knew that he was dull, but had not thought of him as belonging to the class of feeble-minded. She had judged this boy by the 11-year standard and had perhaps been further misled by his normal appearance and exceptionally satisfactory behavior. The Binet test quickly showed that he had a mental level of approximately 9 years. There is little probability that his comprehension will ever surpass that of the average 10-year-old.