One class of teachers seem never to make it a part of their calculation that their pupils will do wrong, and when, any misconduct occurs they are discontented and irritated, and look and act as if some unexpected occurrence had broken in upon their plans.

Others understand and consider all this beforehand.

They seem to think a little, before they go into their school, what sort of beings boys and girls are, and any ordinary case of youthful delinquency or dullness does not surprise them.

I do not mean that they treat such cases with indifference or neglect, but that they _expect_ them, and _are prepared for them_.

Such a teacher knows that boys and girls are the _materials_ he has to work upon, and he takes care to make himself acquainted with these materials, _just as they are_.