During and following the demonstration the oral question can be used to good advantage. Such questions may serve several purposes. By bringing in the element of repetition, they tend to fix the demonstrated methods in the mind of the learner. They assist the learner to discover how well he has comprehended the demonstration, particularly the reasons for performing the work as the instructor has done. The learner is enabled, if the questioning is well done, to identify those methods or ideas which he does not understand. If he is alert, he may find these points cleared up by the answers of others. He may question the instructor until his understanding is clear.