Practicing is everything when it comes down to learning academic material. Solving homework problems on your own, and perhaps reviewing complete step-by-steps solutions is the way to go in terms of catching up with a class you are falling behind.
When you attend to class, the idea is that your instructor will provide you with lovely material for you to follow. You expect to see sample questions resolved in detail, but then the shock comes in: The instructor has too much material to cram in one class, and she will run over everything, in hope students will have retained it all
Wishful thinking it is. Students probably did not catch much. Students need DETAILED solutions to sample problems to get started with their mental processes to approach concepts that are initially alien to them
Check some samples of homework problems with step-by-step solutions