The physical component of the curve is determined by the length of time that you study. On the longer time scales, you may find that the curve does not seem to match the number of units of work in the test. For example, if you have taken four units of AP Chemistry and you do three unit homework, then you will be able to have two units of test left. On the shorter time scales, however, the curve will begin to slope.
The same is true for the curve in tests. The longer the test you take, the steeper the curve will be. This is because more units in the test means that you are doing less homework.
In addition to the physical and logical components of the curve, there is also a logical component to the nature of the curve. The longer your exam, the more advanced your knowledge of chemistry. If you know some basic principles and you took a test that was based on those principles, you may find that you will see the curve in AP Chemistry tests that are longer than four units.
When you review your notes, consider what you may have forgotten to focus on. Ask yourself whether there are areas where you think you have covered a lot of ground, but you may have neglected to do anything about.
What you need to do is include the mechanical aspects of your work and your notes. Look at the curve and decide whether you need to make any changes. You might notice that one test is very much easier than the others. That may indicate that you can get a four unit test done on that day without too much trouble.
You should always check with the class to find out whether the exam is too easy or too hard. Do not take the exam if you are sure that you are going to get a difficult test on that day.
Your last step is to evaluate how many units of work you will need to do. You will probably be able to get by with less work. However, you may not have as much time as you had thought.
There may be a test on Monday, Tuesday, or Wednesday. If you need to do something on Friday, you will probably have a hard time getting back into a study routine. Therefore, you should try to plan for a test early.
Many students find that weekly plans are helpful. They need to concentrate on their papers and exams at least twice a week. If you do this, you will find that you have time to read the book and study for the test, rather than having to do them all at once.
Even if you do not go over the material and have to refresh, you will feel more comfortable in your own learning. After a test, you will usually need to clear your mind and calm down. A test is a way to start a long process of clearing your mind and returning to normal.
You may even find that you do not need to take a test at all. You will probably be able to do all of your work, but you will need to refresh to get the feeling that you were ready to test. Consider this option and you will find that it is more relaxing to have a test then to go through the test feeling drowsy and uncomfortable.