“Think, David, think”

Extract

Because of the many papers that teachers must grade, it sometimes develops that a problem solved incorrectly is checked quickly by the teacher as wrong, and returned to the pupil without the teacher’s having had a sufficient opportunity to know what the pupil was thinking when he did the problem. Some errors may be classified as pure carelessness, but in other cases there may be some basic fundamentals that the pupil has not grasped, and these are important to clarify