General plan of the experiment.?The second experiment to be described was also carried out on the same general plan in the spring and summer of 1910. A whole class of boys (Standards VI and VII), under one teacher, was divided into two equal and parallel groups on the basis of the work done in three preliminary tests in observation. Then one group worked six practice exercises in arithmetic, whilst the other had six practice exercises in obser vation. The two groups again worked together in three final tests in observation. Some important differences, in the standard, age, and sex of the children and in the conduct of the practice exercises, will be noted as the description of the experiment proceeds. The children who did the work.?This experiment was carried out with the first class of a medium-sized boys' school, in the inner ring of the southeastern suburbs of London. The school was the one really poor school in a fairly good district and was not in a high condition pedagogically. But the first class, consisting of Stand ards VI and VII, was a good one and was taught by a very able man who had had some experience in the methods of experimental pedagogy. In considering this work in relation to that of the girls previously described, it must be remembered that it was done by children who were further advanced in their standards, were a year or more older, and was that of boys, who are not naturally so proficient as girls in observational work. But they were in structed and corrected in the course of both sets of their practice exercises, arithmetical and observational, which the girls had not been. They were shown the errors in their arithmetical and in their observational work, both collectively and individually. Another important difference, also, they were, in their tests, allowed a fixed time for the writing up of their observations, namely, forty-five minutes. They were told before every fresh test and exercise the exact marks they had scored in the previous test, the marks for arithmetic being so arranged that they were numerically of the same apparent value as those obtained in the practice tests in ob servation. First-rate work carried approximately the same marks 314