Unnecessary shifts in the mood of a verb can be distracting and confusing to readers. There are three moods in English: the indicative, used for facts, opinions, and questions; the imperative, used for orders or advice; and the subjunctive, used in certain contexts to express wishes or conditions contrary to fact (see G2-g).

The following passage shifts confusingly from the indicative to the imperative mood.

The writer began by reporting the counselor’s advice in the indicative mood (counselor advised) and switched to the imperative mood (pay attention); the revision puts both sentences in the indicative.

A verb may be in either the active voice (with the subject doing the action) or the passive voice (with the subject receiving the action). (See W3-a.) If a writer shifts without warning from one to the other, readers may be left wondering why.

Because the passage began in the active voice (student completes) and then switched to the passive (self-assessment is given, copy is exchanged), readers are left wondering who gives the self-assessment to the teacher and the classmate. The active voice, which is clearer and more direct, leaves no ambiguity.