Answer:
The sentence "Get one half sheet of paper" is: directive.
Step-by-step explanation:
Illocution, in speech acts, refer to the speaker's purpose or intent. An assertive sentence makes a statement. A directive sentence makes a request. A commissive one makes a commitment. An expressive sentence expresses an emotion. Finally, a declarative sentence creates a new state of affairs.
With that in mind, we can see that the sentence "Get one half sheet of paper" is directive. The speaker is asking for or demanding something. A directive sentence can be explicit or implicit. In this case, the verb that expresses such a demand is implicit. To make it an explicit directive, we could add "order" to the sentence: "I order you to get one half sheet of paper."