This may be a dumb question. If so, I apologize. I have now completed all the basic math courses, calculus thru DE, and am taking upper division physics courses. All my math was application based, ie solving problems; we did no proofs whatsoever. So now, while I am able to solve directed problems, when I look at a complex problem, I am sometimes at a loss as to how to start the calculations. Thus my question: are there some keys to look for that would clue one in that this problem might be solved via integration, or this one using a differential equation, etc? Or is this just an indicator that maybe I didnt learn the original information as well as I should have? Thanks for any insights.