You can't write an in-class essay in the same way that you would write a take-home essay. The time limit means you can't waste any time or words and so you really have to quickly get down the essential content and ideas. Here are some tips.
Writing the longer essay (60 points).
Read the prompt carefully. Use the structure of the prompt to make a rough outline of the essay on scratch paper. Make sure you address every element of the prompt.
In-class writing is more a test of your understanding of the course content than of your writing ability. Don't waste time writing a clever intro paragraph. Use the wording of the prompt to write a short intro that restates the question and presents your thesis, which should be an answer to the question.
What have you studied in the course that is relevant/essential to understanding the topic you are writing about? Try to include as much of it as time allows. Are some facts more important than others? Prioritize and make sure you include the information that is most relevant to a complete understanding of the topic.
Of course, it's not enough to list facts and figures, like a take-home essay, there also has to be analysis. Have you made the significance of each piece of evidence clear?
Don't waste time adding information you know from outside of the course or making tangential philosophical extrapolations. Use the essay to show your instructor what you are learning in the course. I don't want to know how smart you are, but what you are learning in my class.
How to prepare
Sometimes an in-class exam will include a longer essay (SA), like those discussed above, and a few (usually four) short identification (ID) essays . With the IDs, you are asked to identify and explain the historical significance (in relation to the history studied in this class) of an important term or concept from the readings. The two types of essay are mirror images of each other. One uses specific factual evidence to support a broad generalization; the other takes a specific fact and shows how it fits into a broader theme or historical question.
SA: General → Specific
ID: Specific → General
If you are given a list of possible long SAs and ID terms in a study guide, try to figure out which ID items might be referenced in an answer to one or more of the long SA questions on the study guide. Your answer to the larger question will suggest one possible significance of the term.
Writing the ID essays (40 points).
Identify the item. Answer as many of the journalistic questions as you can: Who What When Where. EG. Abraham Lincoln was the first US president elected from the Republican Party, in 1860.
Then explain the significance. He is significant because his anti-slavery stance triggered Southern slave states to secede upon his election and he led the Union during the Civil War and played a significant role in the emancipation of the slaves.
Note that this answer is only two sentences long. You could certainly say more about Lincoln, but this would be enough. Also, note that he is such a prominent figure that you are not likely to be asked to identify him. Also, I recommend that you clearly identify the significance, because sometimes the facts suggest a significance. You might say that Lincoln is significant because he was the first Republican elected--not as strong as the other stuff. I want to know what you consider to be the significance.