You're older now, and your time is more valuable, so here's a suggestion of
how to use your time more wisely. It sounds obvious, but many people don't
do it: *read your textbook!* Don't wait until the day before a test,
either. You can get more value from your time by reading the chapter *before*
the lecture on that chapter. During the lecture, the pieces may fall into
place if you've read the book, but if you haven't read the book, there will be
no "pieces" to fall in place; you'll be lost.

Sometimes a teacher who has a real "feel" for the subject will be able to convey that intrinsic understanding to the students, but only those who have a framework already in their brains for that understanding.
So read the book to get that framework.

There are many possible reasons for poor performance on tests, but only a few possible reasons for *surprisingly* poor performance.

If your problem were poor performance, I would just say study harder, party less, etc. But since you do well in homework and class assignments, that's a different story. I have an idea for you to try out. This might help you; it's helped me.

Your problem might be that you *think* you understand just a little bit more than you *really* understand. This can happen if you use reference materials -- textbook, class notes, etc. -- while you're doing your exercises, but you don't use those materials while you're taking a test. You may not realize how heavily you depend on those materials.

So here's my suggestion: when you're doing your homework exercises, if you need to refer to the book or your notes to solve a problem, then go ahead and do that. But when you're done, hide your notes and start over from a blank piece of paper. If you can solve it all the way through, great! Do the next problem. But if you need to peek at your notes while you're solving the problem a second time, go ahead and peek, but then solve the problem a third time -- without peeking.

Will this require you to spend twice or three times as long on your homework? Probably, at first. But if this approach solves your difficulty, then you will find you begin learning at a faster pace, and absorb more during the lectures. After a while, you may find that you are able to do most homework problems the first time without referring to notes at all. When that happens, you'll end up spending just a little extra time on your homework, and whatever time you do spend will be worth it.

You can improve your speed by doing more exercises than are actually
assigned for your homework, and by redoing the exercises from a blank piece of
paper without peeking, as I suggested in my last answer, above. But what
if you've done all that and there are still too many questions on the test for
you to finish in time?

Here's another tip. It's related to my first tip because it addresses the different conditions under which you take a test, compared to the conditions under which you do your homework. When you take a test, you have no notes to work from, so you might feel like a mountain climber without a safety rope: paralyzed. My suggestion is to spend the first few minutes of a test manufacturing the notes you need to work from.

I'll give you an example. My daughter needed to take a test that depended on her knowing the sines, cosines, and tangents of common angles like 45�, 300�, etc. The procedure described in the book and by the teacher is to draw a unit circle, and a ray from the origin that has the given angle with respect to the x-axis, then calculate the point of intersection, and then figure the sine, or cosine, or tangent. That's a great procedure if there are one or two questions. But there were 30 questions. And 45 minutes to do them in. She didn't finish the test, and needless to say got a lousy grade.

I suggested to my daughter that she start with a blank piece of paper, and make a table of sines, cosines, and tangents for all the common angles. She objected at first, but I insisted, so she spent about half an hour, and did the table.

Then I said, now get your time down to five minutes, and you can spend the first five minutes of your test period making this table on scratch paper. There's no rule against that; you simply can't *bring* the table with you to the test.

She practiced, and her second table took her 10 minutes. The third took her 5 minutes. Now at the beginning of a test period, she can scribble out a table in under 3 minutes. This not only helps her by providing a valuable reference during the test, but it also serves as an activity from which she can launch herself into test-taking mode. It breaks the ice in a way.
Read more about this.

For you, it won't necessarily be a table of trig functions, but it'll be something else. The quadratic formula maybe.
Or theorems. Or definitions of terms. How quickly and accurately can you spit
them out on paper? Whatever it is you've been studying, if you can write down a page of helpful hints from memory, then this might be a useful way to begin each test.

Believe it or not, I have the same problem as your daughter. I read a math book, and I think I get it.
Then I close the book, and try a problem, and find to my dismay I can't do it.
Sometimes, students think they get it, but they don't test themselves, so they never know they have a problem until they take a test.
So the most important advice I can give is to read -- I mean *really* read -- the book, and study every example, and truly understand what the author of the book was trying to get across. This is a whole lot different that trying to blast through the material because you have something better to do -- trust me, I've seen both behaviors in my own kids, and as a parent I can tell the difference! Then, write down the statement of the problem for each example (you can do them one at a time as you read them, if you like). Then, with the book
* closed***,** work out the example, showing all the work. Then, open the book, and compare your work to the way it is done in the book. If it's the same (or reasonably close) then go on to the next example. If you get stuck anywhere along the way, here's what I want you to do,
*and this isn't easy,* so pay attention -- I really want you to do this. Understand by rereading the book where you got mixed up or forgetful, and then
*ball up* the piece of paper you were working on, and throw it away. Then write down the statement of the problem again,
*close* the book, and re-do the example from memory. Repeat as long as necessary, even though it might take half an hour for a single example. Don't become discouraged because you think every example will take half an hour -- they won't, please trust me. When you do this you are exercising a weak muscle -- your brain. With each example you do this excruciatingly slow and painful way, you exercise your brain more, and build strength. After a few hours of this exercise, you'll be tired. Take a break. You can't become a strong "mathelete" in a single day. Over the course of several days and weeks, you'll find your brain develops strengths you never knew it had. You'll get the exercises on the first or second try. Your grades will improve. You can thank me, then.