How should one write as someone who was in Pompeii during the volcano eruption?
There are two things that will be important for you to do in this assignment. First, you will need to try to write as if you were really there, being sure to react in ways a real person would have reacted. Second, you will need to make sure that you have your historical facts correct.
I assume that your history teacher has assigned this task. Part of what he or she wants you to do is to imagine what things were like for a person in those times. History teachers today often believe that the experiences of everyday people in the past were important and that part of learning history is trying to understand what those people felt and thought. Therefore, you should really try to put yourself in the place of a person in Pompeii. You should record emotions, not just facts. Are you worried about the volcano? Would you like to run away but cannot for some reason? Is it interfering with your everyday life? Why do you think it is erupting? A person in Pompeii might have thought of all of these things so you should too. In other words, really try to feel what a person in Pompeii would have felt. Do not just write as if you are recording bare facts about the event.
Secondly, you are probably expected to have some historical facts. Make sure you know these. Get the right date for the eruption. Make sure you know what came out of the volcano during the eruption. Look for whatever other facts you were supposed to know and make sure you include them correctly in your writing.
If you get your historical facts right and you write with feeling, you should do well on this assignment.