The class was, by that single pleasant remark, put into the best possible state for receiving the criticisms of the teacher.
"The first fault which I suppose will be found is that some are unfinished." The scholars looked surprised.

They did not expect to have that called a fault.
"How many plead guilty to it ?" A few raised their hands, and the teacher continued: "I suppose that some will be found partly effaced.

The slates were not laid away carefully, or they were not clean, so that the writing is not distinct.

How many find this the case with their work ?" "I suppose that, in some cases, the lines will not be perpendicular, but will slant, probably toward the left, like writing.
"I suppose, also, that, in some cases, the writing will be careless, so that I can not easily read it.

How many plead guilty to this ?" After mentioning such other faults as occurred to him, relating chiefly to the form of the table, and the mere mechanical execution of the work, he said, "I think I shall not look at your slates to-day.