Test Anxiety is a common phenomenon for most students. It is normal and healthy to feel some anxiety before an exam.
Many students complain of knowing the material and then going blank when they take the test.
However, when anxiety begins to affect exam performance it has become a problem. If you hear the material, you will eventually forget it. If you read it you will most likely forget most of it. But if you read it, hear it, and Do it, you will remember it. Understanding comes through application, not meditation.