I can't believe I'm the only one who seems to think textbooks are not optional.
There is just no way you can learn as much from a lecture you attend cold, than from reading a good textbook. If you think you can learn new material from a lecture, you are saying you could learn the same material from a textbook by reading it at the same speed you would read, say, a non-fiction magazine article.
If you can do that, great, you're a genius. But I suspect that the reason people here don't seem to like physics texts is because they have to slow way down when they read them, because the material is so dense. So they cover much more material in an hour of lecture than they do in an hour of reading a text.
But it just doesn't make sense that a prof who is writing as he talks, and spends five minutes talking about the logistics of the next few labs and exams, and ten minutes answering questions from people who missed the last class, can cover anywhere near the amount of material that you could read in an hour. If he does, then OBVIOUSLY he is just hitting the high points. You are not getting the depth you would from a text.
Imagine that when you sign up for a physics class, you can also pick your prof -- not just from the two or three teaching that class at your school, but from the whole world. And that at each lecture, you're not getting whatever quality of lecture he happens to give that day, but his very best thoughts on the subject that he has revised and polished over many years. And that you never miss a word he says because you're taking notes or because somebody next to you asks to borrow a pencil, and you can make him repeat things as many times as it takes until you understand it.
And if it's still unclear, you can get the second best prof to come in and explain it another way. And if you *still* don't get it, you can go down the line of the world's greatest teachers until you do.
That's reading textbooks.
The only thing a book can't teach you is the hands-on aspects of experiments, but that's what labs are for.
Of course, I am assuming that your goal is to learn physics. If that is just a secondary goal, and your main concern is what grade you get, then I guess the books aren't as important. But even if you're just grubbing for grades and mentors, the books will help.
You'll be able to ask much better questions in class, maybe even impress the prof and help your academic career down the road, if you've read a good text on the same material already. You can ask about nuances, instead of the basics. If you can't get the basics from looking at a couple or three texts, then you may not be cut out for physics.
