who commonly enter school late and present high failure rates. The younger children in the study had succeeded in learning how to read in one or two years and had started at age 7. The older children either
started school late or repeated first or second grade one or more times. All children had received school instruction on algorithms for adding, subtracting, multiplying, and dividing including long division, on which they had been instructed 2 months before the beginning of the study.