cases of skipping a grade. In the fourth and fifth grades the boys and girls are approximately the same age, but in the last year in high school the boys are older on the average.
Expressing these tables in school standing in graphic form where 20 millimeters in the horizontal equals one year in age and 30 millimeters in the vertical equals one school grade, the two variables, age and school grade, may be expressed in the form of a continuous line. A third variable, or the average mark for each grade, may also be expressed, assuming the first 6 millimeters in the vertical within a grade to represent a standing between 50 and 60 per cent., the second 6 millimeters, between 60 and 70 per cent.; the third, between 70 and 80 per cent.; the fourth, between 80 and 90 per cent.; and the fifth, between 90 and 100 per cent. Thus it will be noted in the chart that the uppermost curve represents the most precocious child and the lowest curve the most retarded from standpoint of age and grade. No. 6 is the most precocious from the standpoint of age until he reaches 1612 years, and No. 11 the most retarded throughout his school life. On the contrary, comparing the average marks within the grade, No. 11 has higher marks than No. 6, as may be seen by noting the height of the circles in each grade.
Pupils who are relatively poor in the first few grades are relatively poor in the upper grades; that is, poor marks in the early school course are indicative of low standing throughout the school course. Boys and girls of normal school age or under maintain a better school standing, both as to grades and marks, than those over age for grade. The age of entrance after six or seven years determines the age for completing the elementary and high school. With very few exceptions these children progress through the elementary school at the rate of one grade per year, regardless of the chronological age at entrance.
What is the relationship between these two? Accepting the pedagogical age as a fair equivalent of mental development, the first noteworthy fact of general significance is that among these children those of normal school age or younger maintain a better school standing both as to grade and mark than those age for grade. These are the physiologically accelerated or normal pupils. Those above median weight complete the last grade of the elementary school at 12 years, 956 months of age with an average of 84.35, and those below average or of retarded physiological development complete the elementary school work at 13 years, 7712 months of age with an average of 81.72 per cent. Checking the individuals whose curves have been plotted for age, height, weight, lung capacity, school grade and school mark, and giving the results graphically, it may be seen that the majority of children above median height are in or above normal grade and above the average in marks. Of those below median height the majority of children are below or in normal grade and below average mark.
