Once you've written your introduction, if you've dedicated the necessary time and energy and sequenced your events over time (and not the night before) you will be feeling quite confident about your knowledge on the topic you have chosen. You will now be able to specify your hypothesis. If your question includes depression and grades, you will be able to hypothesize what the specific relationship is for your population.

Write your hypothesis so that it can be tested. Think about what the null hypothesis is stemming from your hypothesis, because that is what your statistical tests will be working with.

Much confusion arises in students who do not write their hypothesis clearly. Throughout the semester, when you approach your instructor, you will likely be asked "what is your hypothesis" so know it well, and make sure it is testable and supported by the literature you reviewed.

In fact, it is very difficult to not write a good hypothesis sentence if you've done the work in the correct sequence, usually hypothesis that don't work are those that students came into class with on the first day, not those that resulted from a careful, steady, timely review of the relevant literature.