Define a topic: If you`re allowed to choose your own topic, try to pick something that you already know a bit about and that will hold your interest.
It`s important to give context that will help your reader understand your argument. This might involve providing background information, giving an overview of important academic work or debates on the topic, and explaining difficult terms. Don`t provide too much detail in the introduction—you can elaborate in the body of your essay.
However, this thinking process does not reflect the reality of the situation. In fact, even if your teacher hasn`t given you any hints about the essay question, you do know what it will be about: the concepts and ideas you`ve discussed in the course.
Some students react to the time pressure of essay exams by scribbling down their introduction as soon as they`ve read the question and figuring out their points as they go. While it might seem counter-intuitive, taking five or ten minutes before you start writing in order to draw up a plan will be an enormous time saver.
In longer essays, you can end the introduction by briefly describing what will be covered in each part of the essay. This guides the reader through your structure and gives a preview of how your argument will develop.
Start planning if you can. Although the situation described above sometimes occurs, it`s also very common for professors to give their students a fairly detailed idea of what an essay question will involve in advance of the test day.