I used to do this and I see a lot of students who do this common mistake when studying. Maybe you are working through old homework problems to prepare for an exam in math or physics and you have the solutions in front of you. You get to a certain point and you get stuck, so you check the solution, see what the next action you have to take is, and then continue working through the problem. Eventually you get an answer that may (or may not) be right and check the solution again. If it is, you feel great and move on. If it isn't you compare the work and see what you did wrong and understand the mistake so you move on. All this is a fine way to start studying, but the major mistake is that most students don't go back to that problem and try to do it again. Even if you were able to understand the solution or the mistake you made, you never actually got through the problem completely without aid. So now if you come to this problem on your test, this will be the first time you actually completely the problem completely on your own, if you can remember how to do it. Would you want to put on a performance if you weren't able to recite all of your lines without looking at your notes? It is the same thing for classes like algebra, precalculus, calculus, linear algebra, differential equations, physics, chemistry and biology. Take the extra time after working on a few more problems to come back and try it again. You will give your brain time to let what you learned sink in and get the practice that you need.