The best way to study smart is to get into the subject. Try to figure out why other people find the subject fun. Someone put this material into the curriculum because they loved it; if you can love it too, you will learn without memorizing, your time spent studying will be a joy.
Imagine your professor guiding your study. Ask, what do you think your professor thinks most important? Then spend time on that. Most of what you learn will be on your own. Spend most of your time on the important subjects. You may be wrong, but you'll still be better off since there is never enough time to study everything.
Why is this topic important? On every topic you study, ask that question. What about it is new? How does this contrast, if at all, to the other things I know? Most importantly, don't just learn but also think.
Think about the subject even when not studying. Discuss with others. Make your study into a game; challenge your classmates as you are walking or eating with them. Doing this is far more important than are long study sessions. In fact, you probably can cut back on the amount of time you devote to study. Spending hour after hour can be a crutch, an excuse for being lazy and not actively thinking while you study. But, and this is important, reflect on the subject yourself when you are not "studying".
Make sure you understand the material the first time, before your study sessions. Never put off thinking about it until the exam. If you do it early, you can ask questions to your professor, to your classmates, to yourself. You save enormous time by being ahead of the game. Read the material before the lecture, not afterwards. Yes, the lecture can make the material make sense, but if you read it first, you'll be the student who asks the most thoughtful questions in class.
Take breaks in which you mentally think about what you have just studied. Don't confuse time of study with the depth of study. You're capable of reducing the hours you spend studying if you're recognizing when you begin to drift. If that happens, maybe you should stop studying for a few minutes, walk away, and just think about what you have learned.
Imagine that you are teaching this material to a friend who missed the lecture. How can you present it coherently and thoughtfully? Putting yourself in the shoes of the professor can be very effective in identifying the parts on which you are weak.
I didn't know all this when I was an undergraduate. I picked it up over the years and learned much of it from my better students. It's all obvious advice, once you've heard it, but it often isn't obvious to the student who is panicking over a class that seems too hard. But these are the key methods that I use now, as a retired professor who was writing a book (). These are the methods I use as I try to master the subject of nuclear waste, my latest project. I knew a lot but needed my knowledge to be complete enough to ace the subject. Do you think that once you graduate college, your exams are finished? If you are a physicist like me, then you are taking an exam every time you give a talk, the exam comes at the end when people ask tough questions. I take a review whenever I discuss an advanced topic with colleagues; they can tell how much I know and how much I don't.
These study methods are not ones that you will use for classes alone; you will use them for your entire life, assuming your vocation is one that requires constant and continual learning.
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