There are three hours in each session, according to the usual arrangement, making one hundred and eighty minutes, which, divided among fifty, give about three minutes and a half to each individual.

If the reader has, in his own school, a greater or a less number, he can easily correct the above calculation, so as to adapt it to his own case, and ascertain the portion which may justly be appropriated to each pupil.

It will probably vary from two to four minutes.

Now a period of four minutes slips away very fast while a man is looking over perplexing figures on a slate, and if he exceeds that time at all in individual attention to any one scholar, he is doing injustice to his other pupils.

I do not mean that a man is to confine himself rigidly to the principle suggested by this calculation of cautiously appropriating no more time to any one of his pupils than such a calculation would assign to each, but simply that this is a point which should be kept in view, and should have a very strong influence in deciding how far it is right to devote attention exclusively to individuals.